# Operating Information Letter Honeywell International 1944 E. Sky Harbor Circle Phoenix, AZ 85034

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### OI331-12R6 May 26, 2009 PLEASE DISTRIBUTE TO ALL AFFECT ED FLIGHT CREW MEMBERS AND

MAINTENANCE PERSONNEL

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

APPLICATIONS: All TPE331 Series Engines e quipped with Woodward Fuel Control Units, except TPE331-14/15 series engines.

PURPOSE: The purpose of this OIL is to inform operators of multi-engine aircraft only , of the probable engine responses following a loss of drive between the engine driv en fuel pump and fuel control

governor system. This OIL does not apply to single engine

aircraft

. Reference OI331-18R4 for single engine operation

.

WARNING

This OIL is intended to inform the ope rator of the probable engine responses following a loss of drive between the engi ne driven fuel pump and fuel control governor system. Subsequent handling of the engine and control of the aircraft must be performed/maintained pe r the aircraft’s Pilot Operating Handbook (POH), Aircraft Flight Manual (AF M) or Manufacturer’s Operating Manual (MOM), whichever is appropriate.

DISCUSSION

Engine response following a loss of drive between the engine driven fuel pump and the fuel control governor system is dependent on the phase of opera tion (ground engine start, ground or flight operations) and whether the fuel control is in compliance with one of three engine model specific bulletins (TPE331-A73-0254, TPE331-A73-0262 and TPE331-A73-0271) . If the fuel control installed on the engine is not in compliance with one of the applic able service bulletins, a loss of drive between the engine driven fuel pump and fuel control governo r system will result in a condition where the fuel control underspeed governor will increase fuel flow along the acceleration schedule until reaching the maximum fuel flow stop setting. The fuel flow increase will result in a rapid, uncommanded, uncontrolled increase in fuel fl ow to the engine. Service Bu lletins TPE331-A73-0254, TPE331-A73- 0262 and TPE331-A73-0271 implement an improved overspeed governor mechanism in the fuel control assembly that will limit fuel flow if loss of drive occurs between the fuel pump and the fuelHoneywell International 

# Operating Information Letter 1944 E. Sky Harbor Circle Phoenix, AZ 85034

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### OI331-12R6 May 26, 2009 control assembly. Fuel flow in the modified controls is limited to approximately 180 pph, which represents a low, flight idle, minimum power c ondition. There will be no response to power lever

movements.

ENGINE RESPONSE FOLLOWING A FU EL CONTROL DRIVE FAILURE DURING

DIFFERENT PHASES OF OPERATION

 ENGINES WITH FUEL CONTROLS TH AT ARE NOT IN COMPLIANCE WITH SERVICE BULLETINS TPE331-A73-0254, TPE331-A73-0262 AND TPE331-A73-0271:

- During ground engine starts (with the propeller ON the start locks).

WARNING

- END – During ground engine starts (with the propeller ON the start locks), the engine will experience a rapid uncommanded, uncontrolled acceleration to an overspeed condition sufficient to cause an uncontained separation of high speed rotating

com p onents.

- If an engine exhibits rapidly increasi ng RPM above normal idle values, immediately abort the engine start.

- During ground or flight operation (with th e propeller OFF the start locks), the engine will experience a rapid uncommanded, uncontrolled increase in RPM, torque and/or turbine temperature (the engine may exceed RPM, tor que and/or turbine temperature limits) and

increased forward thrust. Reverse thrust will not be available.

- In the event of a rapid unc ontrolled fuel flow increase with a subsequent increase in RPM, torque and/or turbine temperature, a nd if engine power fails to respond when the power lever is retarde d, shut down the affected engine as soon as possible consistent with safe operation of the aircraft. Do not move the power lever aft of flight idle.

- An uncontrolled fuel flow increase on only one engine could result in a significant asymmetric thrust. Therefore, an uncontrolled fuel fl ow increase is most serious when it occurs to one engine with the opposite engine at a rela tively low power setting, such as during an approach or during the landing rollout.Honeywell International 

# Operating Information Letter 1944 E. Sky Harbor Circle Phoenix, AZ 85034

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### OI331-12R6 May 26, 2009 CAUTION

Be aware that the affected engine (with a malfunctioning control) will exhibit an in crease in power, and if the accepted “dead foot, dead engine” logic is employed, the wrong engine could be shut down. Use caution and include reference to cockpit engine indications to aid in identifying the failure mode and the failed engine.

CAUTION

If an engine exhibits an unc ontrolled fuel flow condition,

never retard the p ower levers aft of fli g ht idle.

CAUTION

If an engine has been shut down in flight or on the ground as a result of exhibiting a rapid uncontrolled increase in RPM, torque and/or turbine temperature, do not attempt a ground start until after inspecting the fuel

control drive in accordance wi th the applicable Service

Bulletin or Maintenance Manual.

 ENGINES WITH FUEL CONT ROLS THAT ARE IN COMP LIANCE WITH SERVICE BULLETINS TPE331-A73-0254, TPE331-A73-0262 AND TPE331-A73-0271:

- During certain high altitude ground engine starts (with the propeller ON the start locks) , the modified fuel control ma y provide fuel flow that is sufficient to cause the engine to accelerate to an overspeed condition and cause an uncontained separation of high speed rotating components. Initiate an emergency s hutdown of the affected engine before the engine speed exceeds 105.5 percent RPM.

- During ground or flight operation (with th e propeller OFF the start locks), the engine will not respond to power lever movements. Fu el flow will be limited to approximately 180 pph, which represents a low flightidle, minimum power condition.

- The pilot may elect to shutdown the affected e ngine consistent with safe operation of the aircraft and the aircraft flight manual.

Note: As with any document that has been revised, as OI331-12 has, discard any and all revisions prior to OI331-12R6. Appl y only the information communicated in OI331-12R6.

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