dhc 8 ice shields
TRANSCRIPT
DHC-8 Ice Shields
Strength testing and repair studies,for the Widerøe airline.
Gisli Eiriksson
Hamza Alzubaidi
Supervisor
Paul Arentzen
This Bachelors Thesis is carried out as a part of the education at the University
of Agder and is therefore approved as a part of this education.
University of Agder, 2014
Faculty of Engineering and Science
Department of Engineering Sciences
Abstract
Widerøe is the largest regional airline in Scandinavia. It operates a fleet
of 42 Bombardier Dash-8 turbo-prop aircraft. Operating in the northern
hemisphere and at an altitude between 0 - 25.000 feet, the conditions for ice
are common. Ice contamination on a propeller will change the aerodynamic
characteristics of the Propeller. If the icing encounter is very severe the ice
catapulted from the propellers can dent the fuselage. A dent in the fuselage
caused by an object impacting it from the outside is very dangerous espe-
cially if it occurs in the pressurized area. To protect the aircrafts fuselage
an ice shield is mounted on the fuselage where the ice usually hits. Once hit
by ice the ice shields often have a somewhat reduced strength against new
ice impact. If such ice shields are not replaced, dents in the fuselage skin
may occur. Full strength ice shields are therefore essential in icy flight con-
ditions to avoid expensive subsequent repair work on the fuselage skin. This
report compares the strength of a new, repaired and damaged ice shields.
Investigates also the reparability of ice shields by assessing the potential of
original strength recovery.
To do the tests we constructed a mockup of an aircraft fuselage (AFM). We
fastened a 5.0 m long PVC pipe to a handrail in the mechatronics labora-
tory. The AFM was placed on the floor under the PVC pipe and the end of
the PVC pipe was directly over the measuring point on the AFM.
We used iron weights wrapped in padding and put them into 1/2 liter plastic
bottles and dropped them down the PVC pipe and measured the deforma-
tion that occurred on the AFM. From that we calculated the average impact
force exerted on the AFM.
From the results we concluded that a repaired ice shield will have equal or
more strength than a new one. The original strength recovery of a damaged
ice shield can be obtained by following the repair procedures.
i
Contents
1 Introduction 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Icing on Aircrafts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2.1 Ice Contamination on Wings . . . . . . . . . . . . . . . . . . 2
1.2.2 Ice Contamination on Propellers . . . . . . . . . . . . . . . . 3
1.3 The Purpose of Ice Shields . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Research Question . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Methodology 5
2.1 Measurement Methods . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.1 Water Indicator . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.2 Strain Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.3 Three Point Flexural Test . . . . . . . . . . . . . . . . . . . 7
2.1.4 Piston / Telescoping Test . . . . . . . . . . . . . . . . . . . 8
2.2 Simulating Ice Impact . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.1 Pendulum Test . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.2 Dropping a Known Mass from a Known Height . . . . . . . 9
3 Procedures 9
3.1 Ice Shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1.1 Repair Procedures . . . . . . . . . . . . . . . . . . . . . . . 9
3.2 Fuselage Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 Reliabilty Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.3.1 Height Reliability Test . . . . . . . . . . . . . . . . . . . . . 11
3.3.2 AFM Reliability Test . . . . . . . . . . . . . . . . . . . . . . 12
3.4 Foam Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.5 Density of Ice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.6 The Impact Force Experiment . . . . . . . . . . . . . . . . . . . . . 15
4 Results 19
4.1 Dropping of Weights . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 New Compared to Damaged Ice Shield . . . . . . . . . . . . . . . . 20
4.3 New Compared to Repaired Ice Shield . . . . . . . . . . . . . . . . 22
ii
4.4 Foam Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.4.1 New Ice Shield . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.4.2 Damaged Ice Shield . . . . . . . . . . . . . . . . . . . . . . . 26
4.4.3 Repaired Ice Shield . . . . . . . . . . . . . . . . . . . . . . . 28
4.5 Impact Force Compared to Kinetic Energy . . . . . . . . . . . . . . 30
4.6 Three Point Flexure Test . . . . . . . . . . . . . . . . . . . . . . . . 31
5 Discussion 32
5.1 Strength Comparison of Ice Shields . . . . . . . . . . . . . . . . . . 32
5.1.1 Remaining Strength of Damaged Ice Shield . . . . . . . . . . 32
5.1.2 Remaining Strength of Repaired Ice Shield . . . . . . . . . . 33
5.2 Comparison of Foam . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.3 Economical Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6 Conclusion 34
6.1 Recommendation for Further Research . . . . . . . . . . . . . . . . 35
References 36
Appendices 38
iii
List of Figures
1 Ice Accumulation on Aircrafts per Hour . . . . . . . . . . . . . . . . 1
2 Propeller Electric Heating Element . . . . . . . . . . . . . . . . . . 3
3 Ice Shield on an Aircraft . . . . . . . . . . . . . . . . . . . . . . . . 4
4 Function Meens Tree . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5 Water Indicator on the AFM . . . . . . . . . . . . . . . . . . . . . . 6
6 Strain Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7 Three Point Flexural Test . . . . . . . . . . . . . . . . . . . . . . . 7
8 Telescoping Curtain Rod . . . . . . . . . . . . . . . . . . . . . . . . 8
9 Dent Repairs from Ice Impact on an Aircraft . . . . . . . . . . . . . 10
10 A Hole in the AFM after a Test Drop . . . . . . . . . . . . . . . . . 12
11 The Impact Force Experiment . . . . . . . . . . . . . . . . . . . . . 15
12 Graph of New Ice Shield Compared to Damaged One with Different
Masses Dropped from a Height of 5.02 m . . . . . . . . . . . . . . . 20
13 Graph of New Ice Shield Compared to Repaired One with Different
Masses Dropped from a Height of 5.02 m . . . . . . . . . . . . . . . 22
14 Graph of New Ice Shield where New, Damaged and Double Foam
are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
15 Graph of Damaged Ice Shield where New, Damaged and Double
Foam are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . 26
16 Graph of Repaired Ice Shield were New, Damaged and Double Foam
are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
17 Graph Comparing Strength of New, Damaged and Repaired Ice Shield 30
18 Three Point Flexure Test Data . . . . . . . . . . . . . . . . . . . . 31
iv
List of Tables
1 Kinetic Energy of Ice Particles Hitting The Ice Shield . . . . . . . . 17
2 Mass for Equivalent Kinetic Energy . . . . . . . . . . . . . . . . . . 17
3 Kinetic Energy of Weights . . . . . . . . . . . . . . . . . . . . . . . 18
4 Mass for Equivalent Kinetic Energy . . . . . . . . . . . . . . . . . . 18
5 Table of New Ice Shield where New, Damaged and Double Foam
are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6 Table of Damaged Ice Shield where New, Damaged and Double
Foam are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7 Graph of Repaired Ice Shield were New, Damaged and Double Foam
are Compared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8 Three Point Flexural Test . . . . . . . . . . . . . . . . . . . . . . . 31
v
List of Symbols
Symbol Meaning
Ek Kinetic Energy [Joules]
Ep Potential Energy [Joules]
F Force [Newton]
g Gravitational Acceleration [m/s2]
h Height [m]
J Joule
m Mass [kg]
r Radius [m]
s Deformation [mm]
V Volume [m3]
Vice Volume of Ice [m3]
Vimp Impact Velocity [m/s]
Vtip Propeller Blade Tip Velocity [m/s]
Vwater Volume of Water [m3]
ω Angular Velocity
ρ Density [kg/m3]
π Pi
List of Abbreviations
Abbreviation Meaning
AFM Aircraft Fuselage Mockup
AIF Average Impact Force [Newton]
MDF Medium-Density Fibreboard
PVC Polyvinyl Chloride
rpm Revolutions Per Minute
vi
Preface
It is with excitement and little sadness that we finish our third and final year
as aeronautical engineering students. We chose to do a bachelor project for the
Widerøe airline because we wanted to solve a real problem on a real aircrafts. The
last five months have been really interesting, educational and sometimes difficult.
It has been fantastic to work with the Widerøe airline on this project. The pinna-
cle moment was when we were invited by Widerøe to Bodø. We spent two whole
days with Geir Johnny Karlsen, one of Widerøe‘s aeronautical engineers where he
helped us find essential information for the project. There we also had the op-
portunity to talk to all of the fantastic people who operate and repair the DHC-8
aircrafts. We got a much deeper understanding of the ice shield problem and the
operation of the DHC-8 aircrafts.
We would like to thank the whole staff at Widerøe airlines for being so willing and
enthusiastic to answer all our questions and for inviting us to Bodø, to experience
a day in an aeronautical engineer‘s life.
We would also like to thank all the personal at the mechatronic and construction
laboratories at UIA.
We would like to give a special thanks to Geir Johnny Karlsen for creating this
project and for helping us through the whole project.
Last but not least we would like to thank our supervisor Paul Arentzen for helping
us through problems and finding solutions.
Hamza Alzubaidi Gisli Eiriksson
vii
1 Introduction
1.1 Background
Widerøe is the largest regional airline in Scandinavia and operates more than 450
flights every day. In Norway the airline fly’s to more than twice as many airports
than any other airline. Widerøe operates a fleet of 42 Bombardier Dash-8 turbo-
prop aircraft previously known as the de Havilland Canada Dash 8 or DHC-8.
The fleet consists of 20 DHC-8 100, 3 DHC-8 Q200, 8 DHC-8 300 and 11 DHC-8
Q400 aircrafts. All the aircrafts are built between 1990 and 2010. Operating in
the northern hemisphere and at an altitude between 0 - 25.000 feet the conditions
for ice are common.[16][17]
1.2 Icing on Aircrafts
Figure 1: Ice Accumulation on Aircrafts per Hour
1
The maximum operating altitude for the 100 - 300 series is 25.000 feet and 27.000
feet for the 400 series. Below−10o C the icing conditions are usually not very severe
however between 0o C and −10o C most ice contamination occurs.[3] Accumulation
of ice on an aircraft can seriously change its aerodynamics and cause problems and
even lead to crashes. The intensity of ice accretion on an aircraft can be light,
moderate and severe. Light icing does not pose any specific restraints on the
behavior of the aircraft. Light icing is defined as more than 10 kg/m2 of ice
an hour. Moderate icing conditions may cause the crew to change heading or
altitude. Moderate icing is defined as more than 60 kg/m2 of ice an hour. Severe
icing conditions which force the crew to immediately change heading or altitude.
Severe icing is defined as more than 120 kg/m2 of ice an hour as seen on Figure
1.[4]
1.2.1 Ice Contamination on Wings
Ice contamination on a wing will change the aerodynamic characteristics of the
wing. It will stall at a lower angle of attack and higher speed. Serious roll control
problems are also not unusual. Even small amounts of ice will have an effect, and
if the ice is rough, it can be a large effect. To clear the ice of the wings of DHC-8
aircrafts a rubber deicing boot is inflated with air, producing ridges to crack and
dislodge any accumulated ice.[11]
2
1.2.2 Ice Contamination on Propellers
Figure 2: Propeller Elec-
tric Heating Element
Ice contamination on a propeller will also change
its aerodynamic characteristics. A propeller is basi-
cally a rotating wing. Ice accretion on the propeller
causes higher engine power requirement for a given
airspeed. To economize electrical power, usually two
propeller blades are de-iced at a time. A heat is ap-
plied to the blades for 10 - 20 seconds followed by a
60 seconds off period. If the icing encounter is very
severe, ice can accumulate on the propeller blades
during the 60 seconds off time. This can cause ice
to shed and impact the fuselage. Propellers are usu-
ally protected only up to 25-30 % of the propeller
disc radius. The reason is that the high velocity of
the propeller blade tip will usually avoid ice forma-
tion, and that centrifugal force will usually cause ice
shedding. Due to very low temperatures at higher
altitudes, ice can accumulate also on the tip. To
clear the ice off the propellers of DHC-8 aircrafts a
de-icing electric heating element is mounted on part
of the leading edge on the propeller blades as seen on Figure 2.[5] The propeller
de-icing system has three selections, off, above −10o C and below −10o C. Each
on timer provides four sequential outputs of either of two frequency cycles depend-
ing on the outside air temperature. Control switch selection of ABOVE −10o C
provides a timer frequency of 10 seconds control power activation followed by a 60
second dwell time. Control switch selection of BELOW −10o C provides timer fre-
quency of 20 seconds control power activation followed by a 60 second dwell time.
In icing conditions the pilots increase the rpm of the propellers both to increase
the airspeed of the aircraft and the centrifugal force on the propeller blades to get
rid of the ice contamination.[Reference... Ice and Rain protection]
3
1.3 The Purpose of Ice Shields
Figure 3: Ice Shield on an Aircraft
When flying in icy conditions, heat
is applied to the propeller blades for
de-icing. The ice that breaks loose
from the rotating propellers is cat-
apulted at a very high speed and
some will hit the fuselage. Without
protection their impact could dam-
age the fuselage skin. To protect
the aircrafts fuselage an ice shield is
mounted on the fuselage where the
ice usually hits. The main purpose
is to absorb most of the energy from
the incoming ice as seen on Figure
3. The ice shield is a glass and Aramid fiber epoxy composite panel covering a
thin foam rubber pad back side.
Once hit by ice the ice shields often have a somewhat reduced strength against
new ice impact. If such ice shields are not replaced, dents in the fuselage skin may
occur. Full strength ice shields are therefore essential in icy flight conditions to
avoid expensive subsequent repair work on the fuselage skin.
1.4 Research Question
Compare strength of a new, repaired and damaged ice shield, examine the degree
of damage and find out how much ice-protection they provide the fuselage. Also
investigate the reparability of an ice shield by assessing the potential of original
strength recovery.
4
2 Methodology
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Figure 4: Function Meens Tree
5
2.1 Measurement Methods
Aircraft fuselage mockup (AFM) is a fuselage simulator that we constructed to
mount the ice shield and the measuring equipment on. We constructed the AFM
from wooden materials, MDF sheets and plywood. The structure was made air-
tight in order to use water indicator as a measurement equipment.
2.1.1 Water Indicator
Figure 5: Water Indicator on the AFM
A hose is mounted through a hole in the airtight AFM structure. It forms a U
shape on the sidewall and is filled halfway with water as seen on Figure 5. When
the impact happens the water should rise since the structure is airtight, and it
should indicate the displacement transferred through the ice shield.
In theory this method should work fine, but in reality it did not. It did not give
the expected indication. We concluded that the volume/deformation ratio was too
low. The water level rose only about 1.0 mm and that was way too little.
6
2.1.2 Strain Gauge
Figure 6: Strain Gauge
A strain gauge was glued to the upper
surface of the curved plywood sheet, and
another to the bottom surface as seen in
Figure 6.
We found out when we started testing
that strain gauges give unreliable mea-
surements when mounted on wood, and
when measuring impact forces.
2.1.3 Three Point Flexural Test
Figure 7: Three Point
Flexural Test
This test was to compare the force needed to
deform ice shields in different conditions, new,
damaged and repaired. It was used to con-
firm how precise our measurements were in the
impact force experiment and if they were reli-
able.
It was clarified that our project does not involve
bending test, and that is why we could not rely on it
as a main test method. The machine used to test the
ice shield is Si Plan universal test machine [A2]. We
cut the ice shield in small specimens that are 0.13 m
long and 0.05 m wide. The specimens were placed
on two iron block supports that were 0.08 m apart, a
loading actuator applies the load exactly in the middle of the ice shield specimens
as seen on Figure 7.
7
2.1.4 Piston / Telescoping Test
Figure 8: Telescoping Curtain Rod
We thought of using some mechanical device in order to measure the deformation
of the AFM. We decided to use an adjustable curtain rod as seen on Figure 8. It
was fasten beneath the thin curved plywood sheet on the AFM. A plastic strip
was mounted on the adjustable curtain rod. When the impact occurred the plastic
strip indicated how much deformation the ice shield experienced during the im-
pact. The deformation was measured with a caliper.
This method worked out to be the most precise way to measure deformation using
the AFM. We continued testing using this method and got useful, comparable
results.
2.2 Simulating Ice Impact
2.2.1 Pendulum Test
A pendulum would hold weights at the end of an arm. A rope would be used to
pull the arm up. When the accurate height is accomplished the rope would be
released. The mass at the end of the arm would hit the ice shield which would be
mounted on the AFM.
8
2.2.2 Dropping a Known Mass from a Known Height
In order to perform a test with any of the measurements mentioned in chapter
2 an ice impact simulator needed to be used. The best way to do that with the
lowest fail margin was to drop an ice from a known height. To hit the ice shield at
the same place all the time a straight PVC pipe was used. The chosen PVC pipe
was 5.0 m long with a diameter of 70 mm as seen on Figure 11.
We chose this method because it is simple, cheap and easy to construct and deal
with.
3 Procedures
3.1 Ice Shield
The ice shield is built up of six fiber layer composites that are 1.12 mm thick, and
a foam rubber pad that is 3.18 mm thick. The outer layers are Cloth-Glass epoxy
pre-impregnated fibers. The inner layers are four layers of Cloth-Aramid Fabric
epoxy pre-impregnated fibers. [A3]
The weight of a new ice shield is about 7 kg while the weight of a repaired ice
shield can be as much as 17 kg. The usual lifetime of a new ice shield is estimated
to be 10 - 15 years, before it has to be repaired due to ice impact damage.[9]
When the ice shield is damaged the next impact can dent the fuselage, because
the remaining strength is impaired.
Damage detection is done by visual control each time the aircraft undergoes an A-
check. A damaged ice shield will be repaired if it has crack or puncture damage[2].
Each type of damage has a specific repair manual that has to be followed in order
to be approved.[A6][A7][A8][A9]
3.1.1 Repair Procedures
There are several types of ice shields that are in use depending on the DHC-8
series. Each of them has their own specific repair drawing that has to be followed
9
in order to repair any type of damage. A manual specifies a repair procedure for
crack and puncture damage.[A6][A7][A8][A9].
When damage can not be identified by the repair drawing, the repair has to be
approved by Bombardier. This procedure costs 500 - 2 000 USD(2 977 - 11 908
NOK, 20/05/2014).[1][9]
When a repair is done, the next step is to paint the ice shield. The paint provides
protection from corrosion, sunlight and moisture. Aramid fibers are weak against
sunlight and moisture.[9] A paint job for a new ice shield costs 5 000 - 5 500 NOK
and for a repaired one 17 000 - 18 000 NOK. The paint procedure can be found in
Appendix A4.[12]
3.2 Fuselage Damage
Figure 9: Dent Repairs from Ice Impact on an Aircraft
10
The fuselage is the main body of an aircraft, and it is a support structure. A dent
in the fuselage caused by an object impacting it from the outside is very dangerous
especially if it occurs in the pressurized area. If the fuselage skin dents inward, it
will bounce out when the cabin pressure is turned on. It bounces back in when
the cabin pressure is turned off. This will cause metal fatigue in the fuselage skin,
and it will definitely become a crack if nothing is done.
Dents in the fuselage pressurized area cannot be more than 0.20 mm in depth.[9]
The repair procedure of a dent in the fuselage is to cut out the surrounding area
of the dent. Then applying doubler over the cut out area as seen on Figure 9.
The stringers surrounding the cut out has to be replaced also.[14] This procedure
is expensive and takes a lot of time, which means the aircraft has to be grounded
which is very costly.
3.3 Reliabilty Tests
3.3.1 Height Reliability Test
To make sure that the test method described in chapter 2.2.2 was reliable, a
reliability test was done. In theory a specific mass dropped from 5.02 m should
have the same kinetic energy as a much smaller mass traveling at higher speed.
To test this theory we dropped a 0.109 kg weight from a height of 5.02 m and got
elastic deformation of 14.5 mm on the AFM. The energy from a 0.109 kg weight
dropped from a height of 5.02 m is equal to:
Ep = mgh = 0.109 kg·9.81 m/s2 · 5.02 m = 5.37 Joule.
Average impact force times deformation is equal to change in kinetic energy
AIF= Ek
s
The impact force will then be AIF= Ep
s= 5.37J
0.0145m= 370.3 N
Next we dropped a 0.544 kg weight from a height of 1.04 m and we got a defor-
mation of 14.5 mm. We calculate the same as before:
Ep = mgh = 0.544 kg ·9.81 m/s2 · 1.04 m = 5.55 Joule.
11
The impact force will then be AIF= Ep
s= 5.55J
0.0155m= 358.1 N
The difference in impact force is only ∆AIF = (370.3N−358.1N)370.3N
= 0.0329 = 3.3 %
The reason for this difference is because we should have gotten the same potential
energy Ep but these weights were the closest we could get. To get the same Ep
the weight dropped from 1.04 m should have been:
m = Ep
gh= 5.37J
9.81m/s2∗1.04m = 0.526 kg
The difference in mass from what the heavier weight should have been (0.526 kg)
and what it actually was (0.544 kg) is:
∆m = (0.544kg−0.526kg)0.544kg
= 0.033 = 3.3 %
This test concluded that the implemented method is reliable and can simulate the
kinetic energy ice particles could have when they hit the ice shield.
3.3.2 AFM Reliability Test
Figure 10: A Hole in the AFM af-
ter a Test Drop
After some tests with the ice shield
mounted on the (AFM) we wanted to
check out if the ice shield was actu-
ally absorbing most of the energy from
the impact. We decided to take the
ice shield of the AFM and test the
AFM without it as seen on Figure
11.
We decided to do a test drop with a mass of
1.549 kg drop it from 5.02 m, because that
was the heaviest mass that we were going
to use in the experiment. It went straight
through the AFM as seen on Figure 10. That concluded that the ice shield is
absorbing most of the impact force and therefore protecting the fuselage.
12
3.4 Foam Test
The painting procedure may affect the foam rubber pad as the last step in the
painting process is to dry the paint in an oven for one hour at 60o C. We did some
research and found out that the operating temperature for this foam material is
from −73o C to 260o C.[13]
But even though we decided to test if the paint procedure could affect the foam. We
heated a piece of foam for one hour at 60o C. There was no change in the material
after heating it. We measured the difference between unheated and heated foam
and could not find any differences.
3.5 Density of Ice
Ice frozen at atmospheric pressure is approximately 8.3 % less dense than liquid
water. The density of ice is 916.7 kg/m3 at 0o C, whereas water has a density of
999.8 kg/m3 at the same temperature. Liquid water is densest, essentially 1000
kg/m3, at 4o C and becomes less dense as the water molecules begin to form the
hexagonal crystals of ice as the freezing point is reached. This is due to hydro-
gen bonding dominating the intermolecular forces, which results in a packing of
molecules less compact in the solid. Density of ice increases slightly with decreasing
temperature and has a value of 934.0 kg/m3 at -180 o C at atmospheric pressure.
However ice gets less dense at high altitude because of low pressure.[?]
Because of the different density of ice at different pressure we did our own density
test of the ice that we used in the experiment. First we pored 1.0 kg of water in a
plastic bag and put in the freezer over night. Then we used a big pot and filled it
half way up with water, thereafter we put the frozen 1 liter ice bag and submerged
it in the water and measured the water displacement. The water displacement was
18 mm.
Volume of a cylinder V = πr2h
Radius of the pot = 0.14 m
13
Vice = πr2h = π · (0.14 m)2 · 0.018 m= 1.108 · 10−3 m3
Vwater = 1.0 · 10−3 m3
∆V = (1.108·10−3m3−1.0·10−3m3)1.0·10−3m3 = 0.108 = 10.8 %
The ice has 10.8 % more volume than water. Then the density is equal to:
ρice == kgm3 = 1.0kg
1.108·10−3m3 = 902 kg/m3
The ice that we will use in our experiment will have density of 902 kg/m3.
14
3.6 The Impact Force Experiment
Figure 11: The Impact Force Ex-
periment
After constructing the AFM and choos-
ing the best measuring method we started
to put everything in the right place for
the impact force experiment. We used
the impact method described in chap-
ter 2.2.2. We fastened the 5.0 m
long PVC pipe to a handrail in the
mechatronics laboratory. The AFM was
placed on the floor under the PVC pipe
and the end of the PVC pipe was di-
rectly over the measuring point on the
AFM.
The measuring device described in chapter
2.1.4 was used. The ice shield was mounted
on the AFM and the PVC pipe was 30 - 40
mm over it.
To make the simulation as real as possi-
ble we used frozen ice blocks with different
mass. For each test we melted and cut the
ice blocks to the right size and mass. We
dropped ice blocks with mass of 0.660 kg,
1.32 kg and 1.98 kg. These masses dropped
from a height of 5.0 m resemble the kinetic
energy from an ice particles of 2.0 · 10−3 kg,
4.0·10−3 kg and 6.0·10−3 kg catapulted from
the propeller at a speed of 178 m/s. For the
1.98 kg ice test we had to use a combination
of ice block and an iron weight because otherwise the ice block would have to be
0.60 - 0.70 m long.
15
We dropped the ice blocks down through the PVC pipe and then measured the
deformation registered with the telescoping curtain rod. It worked fine for a while
but we encountered a problem with the ice and iron weight combination. Some-
times the ice fell before the iron weight. We also noticed that some of the ice blocks
smashed into small pieces and other did not. After close examination we found out
that some ice blocks had many cracks in them after freezing and other had almost
no cracks. The measurements were not accurate because of this problem. The ice
blocks that had many cracks absorbed more energy during the impact than the
ice blocks that did not have any cracks prior to the drop. We also encountered a
problem with the mass of the ice blocks. It was difficult to get the mass exactly
right all the time. It was concluded that we should abort this method and find
another.
We had to find a way to keep the mass constant always. By putting iron weights
wrapped in padding into 1/2 liter plastic bottles we accomplished that. The masses
we used in this experiment were 0.339 kg, 0.664 kg, 1.380 kg, 1.549 kg and 2.370
kg. This method worked really well. All the results we got looked similar. Except
for the 1.549 kg then the results started to look funny and with the 2.370 kg the
AFM broke. The plywood started to crack and delaminate so we stopped the
experiment. We had already gotten all the measurements needed.
The size and mass of the ice particles that are catapulted from the propeller blades
differ a lot. In this experiment we were going to simulate an ice mass of 10.0 ·10−3
kg, 50.0 · 10−3 kg and 100.0 · 10−3 kg. The rotational speed of the propeller we
decided to set to 850 rpm. That is the normal rotational speed of the DHC-
8 aircraft propellers at cruising speed. To find out how much energy those ice
particles have when they hit the ice shield, we first needed to find the propeller
blade tip speed. The diameter of the propellers on the DHC-8 is 4 m. Most ice
particles are catapulted from the propeller blade tip because of centrifugal force
and therefore we use the propeller blade tip velocity for all our calculations.
Vtip = r2πω = 22 · π · 850rpm60s
=178 m/s
We anticipate that the ice particles have that speed when they hit the ice shield.
The kinetic energy that the ice particles have is then:
16
Ek = 12m(Vtip)
2
Table 1: Kinetic Energy of Ice Particles Hitting The Ice Shield
Mass [kg] Vtip [m/s] Ek [J]
0.01 178 158.4
0.05 178 792.1
0.1 178 1584.2
To find out how much mass we had to drop from 5.02 m to get the equivalent
kinetic energy from the ice blocks we first had to find the impact velocity:
Ek = Ep => 12m(Vimp)
2 = mgh => Vimp =√
2gh
Vimp =√
2 · 9.81m/s · 5.02m = 9.92 m/s
Calculation of the mass for the equivalent kinetic energy:
Ek = 12m(Vimp)
2 => m = 2·Ek
(Vimp)2
Table 2: Mass for Equivalent Kinetic Energy
Ek [J] Vimp [m/s] Mass [kg]
158.4 9.92 3.2
792.1 9.92 16.1
1584.2 9.92 32.2
From these calculations as seen in Table 2 it became obvious to us that we had to
simulate much smaller ice particles than 10.0·10−3 kg, 50.0·10−3 kg and 100.0·10−3
kg. The AFM could never handle this kind of impact force from these masses. We
decided then to simulate an ice mass in the range of 1.0 to 10.0 · 10−3 kg.
The masses we used in this experiment were 0.339 kg, 0.664 kg, 1.380 kg, 1.549 kg
and 2.370 kg. The kinetic energy from them is then as seen in Table 3:
17
Table 3: Kinetic Energy of Weights
Mass [kg] Vimp [m/s] Ek [J]
0.339 9.92 16.7
0.664 9.92 32.7
1.380 9.92 67.9
1.549 9.92 76.2
2.370 9.92 116.6
Ek(weights) = 12m(Vimp)
2
Then we find out how much mass the ice particles has to have if it is traveling at
a speed of 178 m/s, we calculate:
Ek = 12m(Vtip)
2 => m = 2Ek
(Vtip)2
Table 4: Mass for Equivalent Kinetic Energy
Ek [J] Vimp [m/s] Mass [kg]
16.7 178 1.05 · 10−3
32.7 178 2.06 · 10−3
67.9 178 4.28 · 10−3
76.2 178 4.81 · 10−3
116.6 178 7.36 · 10−3
From these calculations we see in Table 4 that our simulation with masses of 0.339
kg, 0.664 kg, 1.380 kg, 1.549 kg and 2.370 kg dropped from a height of 5.02 m
have the equivalent kinetic energy as ice particles traveling at a speed of 178 m/s
and with masses 1.05 · 10−3 kg, 2.06 · 10−3 kg, 4.29 · 10−3 kg, 4.81 · 10−3 kg and
7.36 · 10−3 kg.
The average impact force (AIF) exerted on the AFM is then:[6]
18
AIF(0.339kg) = Ek
s= 16.68J
0.017m= 981 N
All the AIF and the deformations results are shown in tables in chapter 4.
4 Results
4.1 Dropping of Weights
As explained in chapter 3.6 we used iron weights wrapped in padding and put
them into 1/2 liter plastic bottles to get constant mass. The masses we used was
0.339 kg, 0.664 kg, 1.380 kg, 1.549 kg and 2.370 kg. In the following sub chapters
we will study results from each mass on new, damaged and repaired ice shield. We
will also compare new, damaged and double foam.
19
4.2 New Compared to Damaged Ice Shield
Damaged Ice Shield
New Ice Shield
Damaged Ice Shield
New Ice Shield
Damaged Ice Shield
New Ice Shield
New Ice Shield
Damaged Ice Shield
950
1150
1350
1550
1750
1950
2150
15 20 25 30 35 40 45 50
Impa
ct F
orce
[N]
Deformation [mm]
New vs Damaged Ice Shield
0.339 kg
0.684 kg
1.380 kg
1.549 kg
Figure 12: Graph of New Ice Shield Compared to Damaged One with Different
Masses Dropped from a Height of 5.02 m
On the graph on Figure 12 we compare new and damaged ice shield. We examine
them under different impact force conditions. We begin with 0.339 kg. The im-
pact force difference is ∆AIF = (1076N−981N)981N
· 100 = 9.7 %. A damaged ice shield
20
transfers 9.70 % more impact force to the AFM than a new one.
The next mass is 0.684 kg. The difference between new and damaged ice shield is
0.86 % where the new ice shield is better.
The next mass is 1.380 kg. The difference between new and damaged ice shield is
6.40 % where the new ice shield is better.
The last mass is 1.549 kg. The difference between new and damaged ice shield is
11.52 % where the damaged ice shield is better. Here the results are opposite to
the other masses and as explained in chapter 5.1.1 the results from 1.549 kg where
unreliable.
21
4.3 New Compared to Repaired Ice Shield
New Ice Shield
Repaired Ice Shield
Repaired Ice Shield
New Ice Shield
Repaired Ice Shield
New Ice Shield
Repaired Ice Shield
New Ice Shield
900
1100
1300
1500
1700
1900
2100
15 20 25 30 35 40 45 50
Impa
ct F
orce
[N]
Deformation [mm]
New vs Repaired Ice Shield
0.339 kg
0.684 kg
1.380 kg
1.549 kg
Figure 13: Graph of New Ice Shield Compared to Repaired One with Different
Masses Dropped from a Height of 5.02 m
On the graph on Figure 13 we compare new and repaired ice shield. We examine
them under different impact force conditions. We begin with 0.339 kg. The impact
force difference is ∆AIF = (981N−927N)927N
· 100 = 5.80 %. A new ice shield transfers
5.80 % more impact force to the AFM than a repaired one.
22
The next mass is 0.684 kg. The difference between new and repaired ice shield is
1.24 % where the repaired ice shield is better.
The next mass is 1.380 kg. The difference between new and repaired ice shield is
4.52 % where the repaired ice shield is better.
The last mass is 1.549 kg. The difference between new and repaired ice shield is
11.52 % where the new ice shield is better.
4.4 Foam Comparison
On the graphs on Figures 14, 15 and 16 we compare new, damaged and double
foam on a new, damaged and repaired ice shields. We examine them under different
impact force conditions.
23
4.4.1 New Ice Shield
Damaged Foam
New and Double Foam
Damaged Foam
New Foam
Double Foam
Damaged Foam
New an Double Foam
New, Damaged and Double Foam
970
1170
1370
1570
1770
1970
2170
2370
16 21 26 31 36 41 46 51
Impa
ct F
orce
[N]
Deformation [mm]
New Ice Shield
0.339 kg
0.684 kg
1.380 kg
1.549 kg
Figure 14: Graph of New Ice Shield where New, Damaged and Double Foam are
Compared
24
Table 5: Table of New Ice Shield where New, Damaged and Double Foam are
Compared
AIF (N) = Avg. impact force in newtons
New Ice Shield Impact velocity = 9.9 m/s
0.339 kg (16.7 J) 0.684 kg (32.7 J) 1.380 kg (67.9 J) 1.549 kg (76.2 J)
Foam/Weight (mm) AIF (N) (mm) AIF (N) (mm) AIF (N) (mm) AIF (N)
Damaged Foam 17 981 22.5 1496 31.5 2155 40 1905
New Foam 17 981 24.2 1390 33 2057 43.5 1752
Double Foam 17 981 24.2 1390 33 2057 45.5 1675
On the graph on Figure 14 we compare new, damaged and double foam on a new
ice shield. We begin with 0.339 kg. The impact force is the same for all types
of foam i.e. 981 N. The next mass is 0.684 kg. The difference between new and
double foam is nothing. Between damaged foam and, new and double foam is
∆AIF = (1496N−1390N)1390N
· 100 = 7.6 %. The mass of 0.684 kg exerts 7.6 % more
impact force on the AFM when a new ice shield has a damaged foam than if it
has new or double foam.
The next mass is 1.380 kg. The difference between new and double foam is also
nothing. Between damaged foam and, new and double foam the difference is 4.8
%. The mass of 1.380 kg exerts 4.8 % more impact force on the AFM when the
ice shield has a damaged foam than if it has new or double foam.
The last mass is 1.549 kg. The difference between new and double foam is 4.6 %
where the new foam is worse. However the difference between damaged foam and
double foam is 3.7 %. The mass of 1.549 kg exerts 13.7 % more impact force on
the AFM when a new ice shield has a damaged foam than if it has double foam
and that is significant difference.
25
4.4.2 Damaged Ice Shield
Damaged Foam Double Foam
New Foam
New Foam
Damaged Foam
Double Foam New Foam Double Foam Damaged Foam
Damaged Foam
New Foam Double Foam 970
1170
1370
1570
1770
1970
2170
15 20 25 30 35 40 45 50 55
Impa
ct F
orce
[N]
Deformation [mm]
Damaged Ice Shield
0.339 kg
0.684 kg
1.380 kg
1.549 kg
Figure 15: Graph of Damaged Ice Shield where New, Damaged and Double Foam
are Compared
26
Table 6: Table of Damaged Ice Shield where New, Damaged and Double Foam
are Compared
AIF (N) = Avg. impact force in newtons
Damaged Ice Shield Impact velocity = 9.9 m/s
0.339 kg (16.7 J) 0.684 kg (32.7 J) 1.380 kg (67.9 J) 1.549 kg (76.2 J)
Foam/Weight (mm) AIF (N) (mm) AIF (N) (mm) AIF (N) (mm) AIF (N)
Damaged Foam 15.5 1076 24 1402 31 2190 49 1555
New Foam 16.5 1011 23 1463 33 2057 42.5 1793
Double Foam 17 981 23.5 1432 31.5 2155 52 1465
For the graph on Figure 15 we do the same comparison as in the previous chapter
but now with damaged ice shield. We begin with 0.339 kg. The impact force with
damaged foam is ∆AIF = (1076N−981N)981N
· 100 = 9.7 % higher than with double
foam i.e. 1076 N compared to 981 N. With new foam the mass exerts 3.1 % more
impact force on the AFM than with double foam.
The next mass is 0.684 kg. The difference between new and damaged foam is 4.4
% where the new foam is worse. The double foam exerts 2.1 % more impact force
on the AFM than the damaged foam.
The next mass is 1.380 kg. The difference between new and double foam is 4.8 %.
Damaged ice shield with double foam exerts 4.8 % more impact force on the AFM
than damaged ice shield with new foam. However the difference between damaged
foam and new foam is 6.5 %. The mass of 1.380 kg exerts 6.5 % more impact force
on the AFM when a damaged ice shield has a damaged foam than if it has new
foam.
The last mass is 1.549 kg. The difference between double and damaged foam is 6.1
% where the damaged foam is worse. However the difference between new foam
and double foam is 22.4 %. The mass of 1.549 kg exerts 22.4 % more impact force
on the AFM when a damaged ice shield has new foam than if it has double foam
and that is significant difference.
27
4.4.3 Repaired Ice Shield
Damaged Foam New and Double
Foam
New and Double Foam
Damaged Foam
Damaged Foam
New and Double Foam
New Foam
Double Foam
Damaged Foam
900
1100
1300
1500
1700
1900
2100
17 22 27 32 37 42 47
Impa
ct F
orce
[N]
Deformation [mm]
Repaired Ice Shield
0.339 kg
0.684 kg
1.380 kg
1.549 kg
Figure 16: Graph of Repaired Ice Shield were New, Damaged and Double Foam
are Compared
28
Table 7: Graph of Repaired Ice Shield were New, Damaged and Double Foam
are Compared
AIF (N) = Avg. impact force in newtons
Repaired Ice Shield Impact velocity = 9.9 m/s
0.339 kg (16.7 J) 0.684 kg (32.7 J) 1.380 kg (67.9 J) 1.549 kg (76.2 J)
Foam/Weight (mm) AIF (N) (mm) AIF (N) (mm) AIF (N) (mm) AIF (N)
Damaged Foam 17.5 953 25 1346 32 2122 43 1772
New Foam 18 927 24.5 1373 34.5 1968 39 1954
Double Foam 18 927 24.5 1373 34.5 1968 42.5 1793
For the graph on Figure 16 we do the same comparison as in the previous chapters
but now with repaired ice shield. We begin with 0.339 kg. The difference between
new and double foam is nothing. Between damaged foam and, new and double
foam the difference is ∆AIF = (953N−927N)927N
· 100 = 2.8 % where the damaged foam
is worse.
The next mass is 0.684 kg. The difference between new and double foam is also
nothing. Between damaged foam and, new and double foam the difference is 2.0
% where the new and double foams are worse.
The next mass is 1.380 kg. The difference between new and double foam is yet
again nothing. However the difference between damaged foam and, new and dou-
ble foam is 7.8 %. The mass of 1.380 kg exerts 7.8 % more impact force on the
AFM when a repaired ice shield has a damaged foam than if it has new or double
foam.
The last mass is 1.549 kg. The difference between double and damaged foam is
1.2 % where the double foam is worse. However the difference between new foam
and damaged foam is 10.3 %. The mass of 1.549 kg exerts 10.3 % more impact
force on the AFM when a repaired ice shield has new foam than if it has damaged
foam.
29
4.5 Impact Force Compared to Kinetic Energy
900
1100
1300
1500
1700
1900
2100
2300
15 25 35 45 55 65
Impa
ct F
orce
[N]
Kinetic Energy [Joules]
Impact Force vs Kinetic Energy
New
Repaired
Damaged
Figure 17: Graph Comparing Strength of New, Damaged and Repaired Ice Shield
On the graph in Figure 17 we compare impact force to the different kinetic energies
from the masses. As seen on the graph the damaged ice shield transfers always
more impact force to the AFM than new or repaired ice shield. We also see that
a repaired ice shield transfers always less impact force to the AFM than new or
damaged ice shield.
30
4.6 Three Point Flexure Test
Table 8: Three Point Flexural Test
Repared Repared Repared New New New Damaged Damaged Damaged
Def. (mm) Force (N) Force (N) Force (N) Force (N) Force (N) Force (N) Force (N) Force (N) Force (N)
0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
2 10 10 20 30 20 30 10 10 50
4 30 30 40 80 40 70 10 20 90
6 50 50 50 130 80 110 20 20 130
8 60 70 70 170 110 150 30 30 170
10 70 80 80 200 150 180 30 40 170
12 80 90 90 230 170 200 40 50 190
14 80 90 90 250 190 210 40 50 200
16 80 90 100 230 200 220 50 60 210
18 80 90 100 230 200 230 50 60 230
20 80 100 100 180 210 230 50 60 230
22 90 100 110 180 200 230 50 60 200
24 90 100 110 180 210 230 50 60 220
26 80 100 110 180 210 230 50 60 190
28 80 100 100 180 210 230 50 60 180
30 80 100 110 180 210 220 40 60 170
-50
0
50
100
150
200
250
0 5 10 15 20
Forc
e (
N)
Deformation (mm)
New
Damaged
Repaired
Damaged
Figure 18: Three Point Flexure Test Data
31
Figure 19 shows the force needed to drive the loading actuator through the ice
shield specimen. These results are very different from the results from the impact
force experiment. The ice shield is made of six layers of composites. Four of the
layers are aramid fibers, which are very flexible. The remaining two layers are
glass fibers. The fiber direction is the same for all six layers and that makes the
structure weak against bending forces. This gives the ice shield high flexibility
which is essential against impact forces.
The result for one of the damaged ice shield specimens was very different from the
other damaged ones. This specimen had intact paint which concluded that the
paint was also important in order to remain the original strength. It was difficult
to break the specimens, but the graph shows the material strength even though it
does not show the break.
5 Discussion
5.1 Strength Comparison of Ice Shields
5.1.1 Remaining Strength of Damaged Ice Shield
Here is a comparison of strength of a new and a damaged ice shield. As mention
in chapter 3.6 the results of the 1.549 kg test was unreliable. It will not be used
in this comparison. As seen on the graph in Figure 12 the result from the 0.684
kg was 0.86 %. That is within the fail margin. Both the other masses show that
a damaged ice shield transfers more impact force to the AFM than a new one. It
can be concluded that the strength of a damaged ice shield is less than of a new
one. How much less strength it has is difficult to measure using this method. It
requires more advanced testing method.
The results from these tests do not give an accurate value of the difference between
a new and a damaged ice shield in reality. The size of the damaged area on
the ice shield is smaller than the impact area of the dropped mass. For more
accurate results the ratio between the impact area and the damaged area should
be considered.
32
5.1.2 Remaining Strength of Repaired Ice Shield
Here is a comparison of strength of a new and a repaired ice shield. As mentioned
in chapter 3.6 the results of the 1.549 kg test was unreliable. It will not be used
in this comparison. As seen on the graph in Figure 13 the AIF difference between
new and repaired ice shield from the 0.684 kg was 1.24 % and the 1.380 kg mass
was 4.52 %, both are within the fail margin.
The result from the remaining mass of 0.339 kg shows that a repaired ice shield
transfers less impact force to the AFM than a new one. It can be concluded that
the strength of a repaired ice shield is equal to or more than the strength of a new
one. Even though the differences are very small and most of them are within the
fail margin. The repaired ice shield did always transfer less impact force to the
AFM than the new one.
5.2 Comparison of Foam
We did set measurement fail margin to 5 %. When the measurements were done
we noticed that the results we got with the 1.549 kg were different then with the
other three smaller masses. After some consideration, we concluded that we could
not trust 1.549 kg results. The material in the AFM had become weaker and the
plywood had probably started to delaminate. When we did the test with the last
mass of 2.370 kg the AFM broke. We also think that the ice shield was starting
to get weaker for the same reasons.
When we compare the graphs on Figure 14, 15, 16 the first thing we see is that
many results can be eliminated due to the 5 % fail margin. With the remaining
results of 0.684 kg on Figure 14, 0.339 kg and 1.380 kg on Figure 15 and 1.380
kg on Figure 16. We see clearly that almost all the time the damaged foam is
performing poorly. The difference between new foam layer and double new foam
layer is almost nothing. However even though a damaged foam layer performs
worse the new foam layer the difference is not that significant. 7.8 % was the most
difference with 1.380 kg on Figure 16 and such a small difference does not justify
any new maintenance procedure where the ice shield is removed just to replace the
foam layer.
33
However it is clear that when an ice shield needs to be repaired, it is essential that
the foam layer is replaced.
5.3 Economical Issues
When an ice shield is damaged and needs to be repaired a decision has to be made
whether to repair it or replace it with a new one. Our results show that a dam-
aged ice shield can regain its original strength back if it is repaired. However the
economical side should be considered. The prices of new ice shields with paint and
the cost of repair for an ice shield are listed below:
New ice shield with paint for the 100 series costs about 39 000 NOK
New ice shield with paint for the 300 series costs about 48 000 NOK
Repair price including paint for ice shield for all DHC-8 series is about 30 000 NOK
From the list above we see that the price difference between a new ice shield for the
100 series and the repair cost is only 9 000 NOK. For the 300 series the difference
is 18 000 NOK. However as explained in chapter 3.1 a repaired ice shield can weigh
up to 10 kg more than a new one. Each DHC-8 aircraft has one ice shield on each
side. If an aircraft has two repaired ice shields, it can weigh up to 20 kg more than
if it had two new ones. This difference will affect the operating cost of the aircraft
with respect to fuel consumption. How much it will affect the operating cost will
not be calculated in this report.
6 Conclusion
A repaired ice shield will have equal or more strength than a new one. The original
strength recovery of a damaged ice shield can be obtained by following the repair
procedures. A damaged ice shield will not give as good ice-impact protection as
a new or repaired one. However it was not possible to examine the remaining
strength related to the degree of damage.
34
6.1 Recommendation for Further Research
Although the experiment is done, there is still a certain amount of uncertainty.
Below is a list of recommendations.
• The measuring method is certainly very important to improve, in order to use
mass transfer closer to reality. The method that should be used to simulate
the ice impact ought to simulate the same mass transfer or momentum as in
the reality. One way that could work is to use air canon to accelerate the ice
to the propper velocity.
• It is also important to consider the size of the impact area because the effect
of the energy is less when the impact area is large. The paint must be
considered in the test because it changed the results as seen in Figure 19.
• The size of the ice shield should also be considered because as seen in Figure
9 it can be seen that the doubler implemented on the fuselage is outside of
protected area of the ice shield. A further study of the size of the impact
area should be done.
35
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TRAINING MANUAL Bod: Widerøe.
[16] Widerøe. (2014). Om selskapet Retrieved Mai 19, 2014, from
http://www.wideroe.no/om-wideroe/om-selskapet
[17] Wikipedia. (2013). Bombardier Dash 8 Retrieved Mai 19, 2014, from
http://en.wikipedia.org/wiki/Bombardier Dash 8
[18] Young, H. D., & Freedman, R. A., (2007). Sears and Zemansky’s university
physics: with modern physics (12th ed.). San Francisco: Pearson/Addison
Wesley.
37
Appendices
A1 Aircraft Fuselage Mockup Drawing
A2 Certificate of Calibration
A3 Ice Shield Drawing
A4 Ice Shield Paint Procedure
A5 Inconclusive Tests
A6 Repair Drawing Crack Damaged
A7 Repair Drawing Generic Procedure
A8 Repair Drawing Permanent Repair Crack Damaged
A9 Repair Drawing Permanent Repair Puncture Damaged
A10 Weight Dropping Test Data
38
A1 Aircraft Fuselage Mockup Drawing
39
40
41
42
A2 Certificate of Calibration
43
44
45
46
47
48
49
A3 Ice Shield Drawing
50
51
52
53
54
A4 Ice Shield Paint Procedure
Ice Shield Painting Procedure.
Information from Axel Olsson painter at Drag Industrier in Bodø.
55
Ice Shield Painting Procedure
When the repair procedure is complete, the ice shield has to be painted. It takes
about 15 man-hours to complete the paint procedure on a repaired ice shield. It
has to be sanded, surface filler has to be applied to the surface, and then it is
sanded again before applying pinhole filler. The surface has to be sanded again,
then the pinhole primer is applied, it is then left to dry for 2-3 hours in a ventilated
room. Next it is sanded again and the excess pinhole primer is smoothed in order
to distribute the composite primer properly.
One hour of drying will be enough before the composite primer can be sanded.
Now the ice shield surface is ready to be painted. The surface is painted two times
with 20 minute intervals. The last step is to dry the paint in an oven for one hour
at 60o C. This paint job costs 17000–18000 NOK.
The procedure for painting a new ice shield takes about 4–5 man-hours. The first
step is to sand the surface, and then apply the primer, and then heating must be
applied to the surface before sanding the primer. The surface can now be painted
with 2 layers paint with 20 minute intervals. The surface only needs to be dried
in an oven for one hour at 60o C. This paint job costs 5000–5500 NOK.
56
A5 Inconclusive Tests
Inconclusive Tests
Dropping of 2.370 Kilogram Weight and Ice Blocks
57
2.370 Kilogram Weight
Table 1: 2.370 kg Mass
2.370 kilogram weight AIF (N) = Avg. impact force in newtons
Displacement in mm Impact velocity = 9.9 m/s
Damaged New Foam Double
Shield/Foam Foam (mm) KE (J) AIF (N) (mm) KE (J) AIF (N) Foam (mm) KE (J) AIF (N)
New 61 116.6 1911
Damaged 66 116.6 1767
Repaired
We tried to test 2.370 kg mass to see if the ice shield and AFM would handle it.
We got two measurements before the AFM broke as seen in Table 1. With only
two numbers we couldn’t compare anything so this test was inconclusive.
Dropping of Ice Blocks
Table 2: 0.660 kg Ice
0.660 kilogram ice AIF (N) = Avg. impact force in newtons
Displacement in mm Impact velocity = 9.9 m/s
Damaged New Foam Double
Shield/Foam Foam (mm) KE (J) AIF (N) (mm) KE (J) AIF (N) Foam (mm) KE (J) AIF (N)
New 33 32.5 984 32.5 32.5 999
Damaged
Repaired 15.5/57 32.5 2095/570
58
Table 3: 1.320 kg Ice
1.320 kilogram ice AIF (N) = Avg. impact force in newtons
Displacement in mm Impact velocity = 9.9 m/s
Damaged New Foam Double
Shield/Foam Foam (mm) KE (J) AIF (N) (mm) KE (J) AIF (N) Foam (mm) KE (J) AIF (N)
New 36.5 64.9 1779 33/24 64.9 1968/2706
Damaged
Repaired 32 64.9 2029
Table 4: 1.980 kg Ice
1.980 kilogram ice AIF (N) = Avg. impact force in newtons
Displacement in mm Impact velocity = 9.9 m/s
Damaged New Foam Double
Shield/Foam Foam (mm) KE (J) AIF (N) (mm) KE (J) AIF (N) Foam (mm) KE (J) AIF (N)
New 38 97.4 2563 32 97.4 3044
Damaged
Repaired 64 97.4 1522
To make the ice impact simulation as real as possible we were going to drop ice
blocks through the PVC pipe. But as described in chapter 3.6 we encountered
a problem when using ice blocks both because it was difficult to get a constant
mass all the time. Also some ice blocks had many cracks in them and others did
not. We got some measurements as seen in Tables 2, 3, 4 but the results were so
strange that we decided to abandon this method and the tests were inconclusive.
59
A6 Repair Drawing Crack Damaged
60
61
62
63
64
65
66
A7 Repair Drawing Generic Procedure
67
68
69
A8 Repair Drawing Permanent Repair Crack Dam-
aged
70
71
72
73
74
75
76
77
A9 Repair Drawing Permanent Repair Puncture
Damaged
78
79
80
81
82
83
84
A10 Weight Dropping Test Data
Weight Dropping Test Data
Results from weight dropping tests done at the mechatronic labora-torium at UIA
85
0.339 kg
Table 1: 0.339 kg Mass
0.339 kilogram weight AIF (N) = Avg. impact force in newtons
Displacement in mm Impact velocity = 9.9 m/s
Damaged KE (J) New Foam Double
Shield/Foam Foam (mm) AIF (N) (mm) KE (J) AIF (N) Foam (mm) KE (J) AIF (N)
New 17 16.7 981 17 16.7 981 17 16.7 981
Damaged 15.5 16.7 1076 16.5 16.7 1011 17 16.7 981
Repaired 17.5 16.7 953 18 16.7 927 18 16.7 927
Damaged Foam1076 N
New Foam 1011 N
Double Foam 981 N
960
980
1000
1020
1040
1060
1080
1100
15 15.5 16 16.5 17 17.5
Damaged Ice Shield 0.339 kg Weight
Damaged Ice Shield
New Foam981 N
Double Foam981 N
Damaged Foam981 N
0
200
400
600
800
1000
1200
0 5 10 15 20
New Ice Shield 0.339 kg Weight
New Ice Shield
Damaged Foam953 N
Double Foam927 N
New Foam927 N
925
930
935
940
945
950
955
17.4 17.5 17.6 17.7 17.8 17.9 18 18.1
Repaired Ice Shield 0.339 kg Weight
Repaired Ice Shield
Damaged Ice Shield 981 N
New Ice Shield981 N
Repaired IceShield 927 N
920
930
940
950
960
970
980
990
16.8 17 17.2 17.4 17.6 17.8 18 18.2
Double Foam
Double Foam
Damaged IceShield 1011 N
New Ice Shield981 N
Repaired Ice Shield 927 N
920930940950960970980990
100010101020
16 16.5 17 17.5 18 18.5
New Foam
New Foam
Damaged IceShield 1076 N
New Ice Shield981 N
Repaired IceShield 953 N
940
960
980
1000
1020
1040
1060
1080
1100
15 15.5 16 16.5 17 17.5 18
Damaged Foam
Damaged Foam
Figure 1: 0.339 kg Mass
86
On the graphs in Figure 1 we compare new, damaged and repaired ice shield with
0.339 kg mass that is dropped from a height of 5.02 m.
• Shield Comparison with Damaged Foam
Damaged ice shield transfers 1076 N impact force to the AFM. New ice shield
transfers 981 N impact force to the AFM. Repaired ice shield transfers 953
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (981N−953N)953N
· 100 = 2.94 %.
This means that the new ice shield transfers 2.94 % more impact force to
the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (1076N−953N)953N
·100 = 12.91
%. This means that the damaged ice shield transfers 12.91 % more impact
force to the AFM than a repaired ice shield.
Comparing new and damaged ice shield: ∆N = (1076N−953N)953N
· 100 = 12.91
%. This means that the damaged ice shield transfers 12.91 % more impact
force to the AFM than a repaired ice shield.
• Ice Shield Comparison with New Foam
Damaged ice shield transfers 1011 N impact force to the AFM. New ice shield
transfers 981 N impact force to the AFM. Repaired ice shield transfers 953
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (981N−927N)927N
· 100 = 5.83 %.
This means that the new ice shield transfers 5.83 % more impact force to
the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (1011N−927N)927N
·100 = 9.06
%. This means that the damaged ice shield transfers 9.06 % more impact
force to the AFM than a repaired ice shield.
87
Comparing new and damaged ice shield: ∆N = (1076N−927N)927N
· 100 = 12.91
%. This means that the damaged ice shield transfers 12.91 % more impact
force to the AFM than a repaired ice shield.
• Ice Shield Comparison with Double Foam
Damaged ice shield transfers 981 N impact force to the AFM. New ice shield
transfers 981 N impact force to the AFM. Repaired ice shield transfers 927
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (981N−927N)927N
· 100 = 5.83 %.
This means that the new ice shield transfers 5.83 % more impact force to
the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (981N−927N)927N
· 100 = 5.83
%. This means that the damaged ice shield transfers 5.83 % more impact
force to the AFM than a repaired ice shield.
Comparing new and damaged ice shield: ∆N = (1076N−927N)927N
· 100 = 12.91
%. This means that the damaged ice shield transfers 12.91 % more impact
force to the AFM than a repaired ice shield.
88
0.684 kg
Table 2: 0.684 kg Mass
0.684 kilogram weight AIF (N) = Avg. impact force in newtons
Displacement in mm Impact velocity = 9.9 m/s
Damaged New Foam Double
Shield/Foam Foam (mm) KE (J) AIF (N) (mm) KE (J) AIF (N) Foam (mm) KE (J) AIF (N)
New 22.5 32.7 1496 24.2 32.7 1390 24.2 32.7 1390
Damaged 24 32.7 1402 23 32.7 1463 23.5 32.7 1432
Repaired 25 32.7 1346 24.5 32.7 1373 24.5 32.7 1373
Damaged Foam1496 N
Double Foam1390 N
New Foam1390 N
1380
1400
1420
1440
1460
1480
1500
1520
22 22.5 23 23.5 24 24.5
New Ice Shield 0.684 kg Weight
New Ice Shield
Damaged Foam1402 N
New Foam1463 N
Double Foam1432 N
1390
1400
1410
1420
1430
1440
1450
1460
1470
22.8 23 23.2 23.4 23.6 23.8 24 24.2
Damaged Ice Shield
Damaged Ice Shield
Damaged Foam1346 N
Double Foam1373 N
New Foam1373 N
1340
1345
1350
1355
1360
1365
1370
1375
24.4 24.5 24.6 24.7 24.8 24.9 25 25.1
Repaired Ice Shield
Repaired Ice Shield
New Ice Shield1496 N
Damaged IceShield 1402 N
Repaired IceShield 1346 N
13201340136013801400142014401460148015001520
22 22.5 23 23.5 24 24.5 25 25.5
Damaged Foam
Damaged Foam
Damaged IceShield 1463 N
New Ice Shield1390 N
Repaired Ice Shield 1373 N
136013701380139014001410142014301440145014601470
22.5 23 23.5 24 24.5 25
New Foam
New Foam
Damaged Ice Shield 1432 N
New Ice Shield1390 N
Repaired Ice Shield 1373 N1370
1380
1390
1400
1410
1420
1430
1440
23.4 23.6 23.8 24 24.2 24.4 24.6
Double Foam
Double Foam
Figure 2: 0.684 kg Mass
89
On the graphs in Figure 2 we compare new, damaged and repaired ice shield with
0.684 kg mass that is dropped from a height of 5.02 m.
• Ice Shield Comparison with Damaged Foam
Damaged ice shield transfers 1402 N impact force to the AFM. New ice shield
transfers 1496 N impact force to the AFM. Repaired ice shield transfers 1346
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (1496N−1346N)1346N
· 100 = 11.14
%. This means that the new ice shield transfers 11.14 % more impact force
to the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (1402N−1346N)1346N
·100 = 4.16
%. This means that the damaged ice shield transfers 4.16 % more impact
force to the AFM than a repaired ice shield.
Comparing new and damaged ice shield: ∆N = (1496N−1402N)1402N
·100 = 6.70 %.
This means that the new ice shield transfers 6.7 % more impact force to the
AFM than a damaged ice shield.
• Ice Shield Comparison with New Foam
Damaged ice shield transfers 1463 N impact force to the AFM. New ice shield
transfers 1390 N impact force to the AFM. Repaired ice shield transfers 1373
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (1390N−1373N)1373N
· 100 = 1.24 %.
This means that the new ice shield transfers 1.24 % more impact force to
the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (1463N−1373N)1373N
·100 = 6.56
%. This means that the damaged ice shield transfers 6.56 % more impact
force to the AFM than a repaired ice shield.
90
Comparing new and damaged ice shield: ∆N = (1463N−1390N)1390N
·100 = 5.25 %.
This means that the damaged ice shield transfers 5.25 % more impact force
to the AFM than a new ice shield.
• Ice Shield Comparison with Double Foam
Damaged ice shield transfers 1432 N impact force to the AFM. New ice shield
transfers 1390 N impact force to the AFM. Repaired ice shield transfers 1373
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (1390N−1373N)1373N
· 100 = 1.24 %.
This means that the new ice shield transfers 1.24 % more impact force to
the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (1432N−1373N)1373N
·100 = 4.29
%. This means that the damaged ice shield transfers 4.29 % more impact
force to the AFM than a repaired ice shield.
Comparing new and damaged ice shield: ∆N = (1432N−1390N)1390N
·100 = 3.02 %.
This means that the damaged ice shield transfers 3.02 % more impact force
to the AFM than a new ice shield.
91
1.380 kg
Table 3: 1.380 kg Mass
1.380 kilogram weight AIF (N) = Avg. impact force in newtons
Displacement in mm Impact velocity = 9.9 m/s
Damaged New Foam Double
Shield/Foam Foam (mm) KE (J) AIF (N) (mm) KE (J) AIF (N) Foam (mm) KE (J) AIF (N)
New 31.5 67.9 2155 33 67.9 2057 33 67.9 2057
Damaged 31 67.9 2190 33 67.9 2057 31.5 67.9 2155
Repaired 32 67.9 2122 34.5 67.9 1968 34.5 67.9 1968
Damaged Foam2155 N
New Foam2057 N
Double Foam2057 N
2040
2060
2080
2100
2120
2140
2160
31 31.5 32 32.5 33 33.5
New Ice Shield
New Ice Shield
Damaged Foam2122 N
Double Foam1968 N
New Foam1968 N
1960198020002020204020602080210021202140
31.5 32 32.5 33 33.5 34 34.5 35
Repaired Ice Shield
Repaired Ice Shield
Damaged Ice Shield 2190 N
New Ice Shield2155 N
Repaired IceShield 2122 N
2110212021302140215021602170218021902200
30.8 31 31.2 31.4 31.6 31.8 32 32.2
Damaged Foam
Damaged Foam
Damaged IceShield 2057 N
New Ice Shield2057 N
Repaired IceShield 1968 N1960
19701980199020002010202020302040205020602070
32.5 33 33.5 34 34.5 35
New Foam
New Foam
Damaged Ice Shield 2155 N
New Ice Shield2057 N
Repaired IceShield 1968 N1950
2000
2050
2100
2150
2200
31 32 33 34 35
Double Foam
Double Foam
Damaged Foam2190 N
Double Foam2155 N
New Foam2057 N
2040
2060
2080
2100
2120
2140
2160
2180
2200
30.5 31 31.5 32 32.5 33 33.5
Damaged Ice Shield
Damaged Ice Shield
Figure 3: 1.380kg Mass
92
On the graphs in Figure 3 we compare new, damaged and repaired ice shield with
1.380 kg mass that is dropped from a height of 5.02 m.
• Ice Shield Comparison with Damaged Foam
Damaged ice shield transfers 2190 N impact force to the AFM. New ice shield
transfers 2155 N impact force to the AFM. Repaired ice shield transfers 2122
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (2155N−2122N)2122N
· 100 = 1.55 %.
This means that the new ice shield transfers 1.55 % more impact force to
the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (2190N−2122N)2122N
·100 = 3.21
%. This means that the damaged ice shield transfers 3.21 % more impact
force to the AFM than a repaired ice shield.
Comparing new and damaged ice shield: ∆N = (2190N−2155N)2155N
·100 = 1.62 %.
This means that the damaged ice shield transfers 1.62 % more impact force
to the AFM than a new ice shield.
• Ice Shield Comparison with New Foam
Damaged ice shield transfers 2057 N impact force to the AFM. New ice shield
transfers 2057 N impact force to the AFM. Repaired ice shield transfers 1968
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (2057N−1968N)1968N
· 100 = 4.52 %.
This means that the new ice shield transfers 4.52 % more impact force to
the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (2057N−1968N)1968N
·100 = 4.52
%. This means that the damaged ice shield transfers 4.52 % more impact
force to the AFM than a repaired ice shield.
93
Comparing new and damaged ice shield: There is no difference between new
and damaged ice shield with new foam.
• Ice Shield Comparison with Double Foam
Damaged ice shield transfers 2155 N impact force to the AFM. New ice shield
transfers 2057 N impact force to the AFM. Repaired ice shield transfers 1968
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (2057N−1968N)1968N
· 100 = 4.52 %.
This means that the new ice shield transfers 4.52 % more impact force to
the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (2155N−1968N)1968N
·100 = 9.50
%. This means that the damaged ice shield transfers 9.50 % more impact
force to the AFM than a repaired ice shield.
Comparing new and damaged ice shield: ∆N = (2155N−2057N)2057N
·100 = 4.76 %.
This means that the damaged ice shield transfers 4.76 % more impact force
to the AFM than a new ice shield.
94
1.549 kg
Table 4: 1.549 kg Mass
1.549 kilogram weight AIF (N) = Avg. impact force in newtons
Displacement in mm Impact velocity = 9.9 m/s
Damaged New Foam Double
Shield/Foam Foam (mm) KE (J) AIF (N) (mm) KE (J) AIF (N) Foam (mm) KE (J) AIF (N)
New 40 76.2 1905 43.5 76.2 1752 45.5 76.2 1675
Damaged 49 76.2 1555 42.5 76.2 1793 52 76.2 1465
Repaired 43 76.2 1772 39 76.2 1954 42.5 76.2 1793
Damaged Foam1905 N
New Foam1752 N
Double Foam1675 N1650
1700
1750
1800
1850
1900
1950
38 40 42 44 46
New Ice Shield
New Ice Shield
New Ice Shield1905 N
Repaired IceShield 1772 N
Damaged IceShield 1555 N
1500155016001650170017501800185019001950
40 42 44 46 48 50
Damaged Foam
Damaged Foam
New Ice Shield1752 N
Damaged IceShield 1793 N
Repaired IceShield 1954 N
1700
1750
1800
1850
1900
1950
2000
38 39 40 41 42 43 44
New Foam
New Foam
Repaired IceShield 1793 N
New Ice Shield 1675 N
Damaged Ice Shield 1465 N
1400145015001550160016501700175018001850
40 42 44 46 48 50 52 54
Double Foam
Double Foam
New Foam1793 N
Damaged Foam1555 N
Double Foam1465 N
1400145015001550160016501700175018001850
40 45 50 55
Damaged Ice Shield
Damaged Ice Shield
New Foam1954 N
Double Foam1793 N Damaged Foam
1772 N1750
1800
1850
1900
1950
2000
38 39 40 41 42 43 44
Repaired Ice Shield
Repaired Ice Shield
Figure 4: 1.549 kg Mass
95
On the graphs in Figure 4 we compare new, damaged and repaired ice shield with
1.549 kg mass that is dropped from a height of 5.02 m.
• Ice Shield Comparison with Damaged Foam
Damaged ice shield transfers 1402 N impact force to the AFM. New ice shield
transfers 1496 N impact force to the AFM. Repaired ice shield transfers 1346
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (1496N−1346N)1346N
· 100 = 11.14
%. This means that the new ice shield transfers 11.14 % more impact force
to the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (1402N−1346N)1346N
·100 = 4.16
%. This means that the damaged ice shield transfers 4.16 % more impact
force to the AFM than a repaired ice shield.
Comparing new and damaged ice shield: ∆N = (1496N−1402N)1402N
·100 = 6.70 %.
This means that the new ice shield transfers 6.7 % more impact force to the
AFM than a damaged ice shield.
• Ice Shield Comparison with New Foam
Damaged ice shield transfers 1463 N impact force to the AFM. New ice shield
transfers 1390 N impact force to the AFM. Repaired ice shield transfers 1373
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (1390N−1373N)1373N
· 100 = 1.24 %.
This means that the new ice shield transfers 1.24 % more impact force to
the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (1463N−1373N)1373N
·100 = 6.56
%. This means that the damaged ice shield transfers 6.56 % more impact
force to the AFM than a repaired ice shield.
96
Comparing new and damaged ice shield: ∆N = (1463N−1390N)1390N
·100 = 5.25 %.
This means that the damaged ice shield transfers 5.25 % more impact force
to the AFM than a new ice shield.
• Ice Shield Comparison with Double Foam
Damaged ice shield transfers 1432 N impact force to the AFM. New ice shield
transfers 1390 N impact force to the AFM. Repaired ice shield transfers 1373
N impact force to the AFM.
Comparing new and repaired ice shield: ∆N = (1390N−1373N)1373N
· 100 = 1.24 %.
This means that the new ice shield transfers 1.24 % more impact force to
the AFM than a repaired ice shield.
Comparing damaged and repaired ice shield: ∆N = (1432N−1373N)1373N
·100 = 4.29
%. This means that the damaged ice shield transfers 4.29 % more impact
force to the AFM than a repaired ice shield.
Comparing new and damaged ice shield: ∆N = (1432N−1390N)1390N
·100 = 3.02 %.
This means that the damaged ice shield transfers 3.02 % more impact force
to the AFM than a new ice shield.
97