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System Safety in the Military

Jet Utilization Stage

Marco Geering Department Manager

Military Jet&Missiles Engineering / CSEP

RUAG Aviation

Military Aircraft Division

ETH ZH, 01.09.14

06.10.2014 RUAG Division 2

CH Jet System Safety - Agenda

1. Introduction

2. Military System Safety

3. System Safety Requirements

4. Examples

6.1 Planing Link Failure

6.2 Operational Impact on Design

5. Summary

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CH Jet System Safety – Introduction

http://www.despotou.eu/

MIL-STD-882E


CH Jet System Safety – Introduction

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SSPP describes in details how RA as an contractor fulfils Swiss

Government system safety requirements throughout all phases of the

system life cycle.

SSPP does not cover operational issues which shall be managed by ORM

from the operator


CH Jet System Safety – MIL System Safety

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The system safety applied for military weapon systems is different from the

civilian approach due to:

The residual (mishap) risk acceptance by the appropriate authority is unique

to military. The “As Low As Reasonably Practicable” ALARP philosophy is

applied in Switzerland.

The level of safety

= f (situation)

Urgent Ops needs:

- SAR

- Intercept

- AAR etc

MIL Ops

- Recce

- Dog Fight

- Weapons etc

Unusual designs to

meet higher

performance

requirements


CH Jet System Safety – Requirements Process

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Hazard identification

Hazard/risk assessment Risk avoidance

Risk control

Risk transfer

Risk acceptance

Risk tracking and

monitoring


CH Jet System Safety – Requirements Process - Identify

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Laws

Regulations

etc

I-Level

Ops

OEM

FMS

OSTR

Example F/A-18 2013

• 112 technical ASR

• 1’515 OEM/USN/FMS Messages

• 2’233 defect reports (O-/I-/D-Level)


CH Jet System Safety – Requirements Process – Analyse - Hazard Risk Index

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CH Jet System Safety – Requirements Process - Analyse

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1. Review item failure mode

2. Assess the severity

3. Identify failure rates or

probabilities of occurence

4. Identify the critical

operational environment

and associated ops factors

5. Identify mitigating or

exacerbing factors

6. Select the worst credible

risk


CH Jet System Safety – Requirements Process - Treat

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Risk mitigation mesures are

1. Design changes

2. Incorporate safety devices

3. Provide warning devices

4. Develop procedures and training

Example: TEF Connecting Link Modification

06.10.2014 RUAG Division 11 06/10/2014 11

CH Jet System Safety – Requirements Process - Monitor

• System Monitoring

• SSWG

CH Jet System Safety – Example Planing Link Failure




(Status 2008)

MLG PLF: If connecting or planing

link fails due to buckling than the

wheel axis is not blocked anymore =>

instable roll out

Probability Level is set to

probable (Swiss has a PLF rate

of 10 / 100k FH)

Severity is set to critical

HRI 5 (serious risk)

World wide issue



Switzerland has done shock absorber flight tests to gave inputs to the correct

modelling of the MLG behaviour (static, dynamic). The following mitigation

actions have been taken:

• Re-design of planing link machanism

• New rigging procedures

• New shock absorber servicing tolerances

CH Jet System Safety – Example Operational Impact on Design




Hornet F/A-18C/D procurement Requirements

Improved Air-To-Air Load Factor Capability

Swiss G-Load > USN G-Load

Service Life Criteria

Swiss hours > USN Hours

Swiss usage spectrum about three times more

severe than USN usage (CH F/A-18 A/A ops,

shorter times to mil training area)

Design Change Center Fuselage

Titanium parts (Ti-6AI-4V) instead of

Aluminium (7075-T7351)



Swiss Full Scale Fatigue Test

Fracture and maintenance critical

parts meet 2 Swiss lifetimes of

durability life

Fracture critical parts (safety of

flight parts) meet 2 Swiss lifetimes

of damage tolerance life for the

mutual agreed initial flaw sizes

Results

Updated Swiss Fatigue Inspection

Schedule based on FSFT results

Structural Refurbishment Program:

re-design of critical areas such as

Crease Longeron, Fuel Cell Floor,

Fuel Barrier Web, Upper Outboard

Longeron etc.


CH Jet System Safety - Summary

Residual risk acceptance is the main difference between civil and

military safety

The system safety program is based on established processes

MIL-STD-882

Good collaboration between different stakeholder are a key factor

(ORM by Operator, system /usage monitoring by industry, acceptance

(technical) by Military Airworthiness Authority)


CH Jet System Safety - Summary

It takes a minute to write a safety rule

It takes a hour to hold a safety meeting

It takes a week to plan a safety program

It takes month to put it into operation

It takes a year to win a safety award

It takes a lifetime to make a safe worker

IT TAKES ONE SECOND TO DESTROY IT ALL WITH ONE ACCIDENT

RUAG Aviation 20

Thank you for your attention!

Questions

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