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TFE731 Fall 2005
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MSP Parts Ordering
— Lanny Renshaw
Many customers call requesting parts, asking if those parts are covered by MSP. MSP will cover parts which are listed in the Honeywell IPC for that engine model. For freight, MSP Gold will cover charges for LRUs (Line Replaceable Units) when certain conditions are met. Counter-to-counter charges are usually not covered. When ordering parts, have the MSP number and the engine S/N with current times and cycles. Also, we are not allowed to order multiples of filters, igniters, SOAP kits, etc., only one per engine.
Service Bulletin Updates
— Lanny Renshaw
SB TFE731-73-3149 for engine models 731-2/-3/- 4/-5 & TFE731-73-5136 for engine models 731-20/- 40/-60 - Replace fuel pump filter element, dated 9.12.05. This SB was created to replace P/N 897513- 1. The old fuel filter does not meet the design intent for debris retaining capacity. The replacement filter P/N is 897830-1. Honeywell recommends complying with this SB at the next cause for the fuel filter removal (routine inspections) and is covered by MSP.
SB TFE731-76-3076R1 - Rework N1 DEECs to address Lean Blowout (LBO) on the TFE731-2 engines installed on the Learjet aircraft, dated 7.1.05. To rework the N1 DEEC, new software must be uploaded into the DEEC. There have been DEECs that will not accept the new software even after multiple attempts. In this case the DEEC needs to be replaced. Honeywell is currently working on new software/procedures to prevent the replacement of the DEEC. Honeywell does not have the latest DEECs in-stock and the only way to comply with this SB is to upload the new software even for the replacement DEEC that you may have to order. If you plan to comply with this SB, we recommend a soft aircraft schedule for a few days in case a replacement DEEC is needed.
SB TFE731-79-3069 - Replace oil filter bypass indicator valve, dated 2.16.05, applies to TFE731-2/-3/-4/-5 engine models. The reason is that the current indicator P/N 3070246-4 may give a false by-pass indication due to the thermal lockout set point being set too low. Honeywell has a new indicator, P/N 3070246-5, with a higher lockout setting. If the indicator continues popping even after following the troubleshooting procedure for Oil System Contamination Check in the LMM, replace it with the new P/N. If the new indicator continues to pop, contact your local Honeywell Service Center for further troubleshooting assistance.
Troubleshooting Procedures
— Lanny Renshaw
When troubleshooting operational squawks, following the troubleshooting steps in the maintenance manual is usually the best procedure. A close second is always common sense. For example, we just had an engine with a high oil temperature indication but a normal oil pressure. Per the troubleshooting procedure, first:
- check oil level - OK,
- check the airframe indication - OK,
- check the oil temperature bulb - OK,
- check oil pressure - OK,
- replace air/oil cooler temperature control valve - OK,
- replace fuel/oil cooler - OK
- replace air/oil coolers, as a last resort.
Many times, the air/oil cooler temperature control valve has failed and does not allow the oil to flow into the air/oil coolers, causing the oil temp to rise. But to access this valve, you must remove the thrust reverser/after-body and inner by-pass ducts and depending on aircraft/engine models, you may have to remove the engine as well. Rule out some of the easier components first such as the fuel/oil cooler which is located on the lower, right side of the engine. In our case, the fuel/oil cooler was defective. By replacing the fuel/oil cooler first, we were able to get the aircraft flying sooner than if we had followed the troubleshooting procedures step-by-step.
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