Operating Information Letter

Honeywell International

1944 E. Sky Harbor Circle Phoenix, AZ 85034

1 of 2 OI331-26R1 September 22, 2014

PLEASE DISTRIBUTE TO ALL AFFECTED FLIGHT CREW MEMBERS AND MAINTENANCE PERSONNEL

TO: All Owners/Operators, Airframe Manufacturers, Distributors, Sales and Service Organizations, and Field Service Representatives

APPLICATIONS: All TPE331 Models:

TPE331-All

PURPOSE:

The purpose of this Operating Information Letter is to provide a description of the engine symptoms and recommended actions in the event of an uncoupling event. An uncoupling scenario is defined as a disengagement of any of the engine gearbox components which make up the gear reduction drive from the ring gear support to the splined propeller shaft coupler. This separation typically occurs while the engine is at higher torque levels, but may also occur at lower torque levels. This OIL is not intended to be used in lieu of the applicable aircraft manuals. If these recommendations conflict with aircraft manual procedures, Honeywell recommends you contact the aircraft OEM for clarification.

Operating Information Letter

Honeywell International

1944 E. Sky Harbor Circle Phoenix, AZ 85034

2 of 2 OI331-26R1 September 22, 2014

WARNING

WARNING: In the event of an uncoupling event where the engine is operating and the propeller is stopped and feathered, retarding the power lever to flight idle may result in the unfeathering of the propeller, repositioning of the freewheeling propeller blades at the low pitch stop and subsequent rotation of the propeller, with no negative torque sensing (NTS) occurring. Propeller blades at the low pitch stop will create more drag than in the feather position and could result in the loss of aircraft control, serious injury or death to personnel and loss of the aircraft.

DISCUSSION The propeller of an engine that has experienced an uncoupling scenario will move quickly toward feather until the feather stop position blade angle is reached; at the same time, the engine will accelerate to the Over Speed Governor (OSG) set point of approximately 104% RPM and remain at that speed until the engine is shut down. Typical propeller and engine parameters following an uncoupling event:

Propeller blades.Feathered Engine speed..104% RPM (Approximate) Torque...0% (Approximate)

In the event of an engine uncoupling, the pilot should follow the emergency engine shut down and securing procedures in accordance with the FAA approved Aircraft Flight Manual.

Note: Prior to performing the emergency shutdown procedure, advancing and maintaining the Power Lever (PL) of the affected engine to the full forward position will ensure the availability of beta follow-up and that the propeller blades will remain in the feathered position.

Movement of the PL to the maximum forward position following the uncoupling event does not change the operating parameters of the engine. However, reducing the PL after a decouple event may cause the propeller to come out of feather, slew toward the low pitch stop and to begin rotating, which will result in increased drag. Additionally, depending upon the airspeed of the airplane during the event, it could result in a propeller overspeed (greater than 100% propeller speed). The increased drag and the potential of a propeller overspeed can be avoided by advancing and maintaining the power lever fully forward until the engine has been shut down.

For further assistance, contact the Honeywell Technical Operations Center at 1-800-601-3099 (U.S.) or 1-602-365-3099 (International).

END

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