JT15D Engines Fall 1999
- Experiencing Some ITT Fluctuations?
- Be Aware Of Pratt & Whitney Support
- OJT15D-5 & -5D TBO Escalation
- Always Preload Your Torque Wrench
Experiencing Some ITT Fluctuations?
Duncan has recently received some calls relating to fluctuations of ITT in flight. Though a landing should be made as soon as practical for repair, sometimes some troubleshooting can be done in flight.
When the circuit breaker is reset and the fluctuation disappears for a period of time, it may appear that the problem is the indicator, but don’t order a gauge over your cellphone yet. First, the ITT gauges are extremely reliable. Secondly, 95% of problems of this nature have been wire breakage where airframe wiring meets the engine inlet temperature probe. If this is the case, it is easily repaired with new alumel or chromel terminals. Part numbers are 1-322337-0 and 1-322338-0, respectively.
Having overall engine balance checked and possibly balancing the fan may help alleviate future terminal breakage.
For more info, contact Ken Kuchenreuther in BTL at 800.525.2376 or Doug Alleman in LNK at 800.228.4277.
Be Aware Of Pratt & Whitney Support
Operators should be aware of Pratt & Whitney’s Support Program at hot section inspection on your JT15D-4, 4B and 4D engines. On certain gas generator cases, wear occurs between diffuser tubes and the inner jam-ring. The cost to repair this can be as high as $35,000 per engine, just for parts. You can save approximately half of this cost if the engine qualifies for Pratt & Whitney’s Commercial Support program. There is also a labor allowance. Parts that may be covered, if applicable, are the diffuser pipe, clamp, bolts and deflector ring. The program expires on December 31, 2000.
For more info, contact Ken Kuchenreuther in BTL at 800.525.2376 or Doug Alleman in LNK at 800.228.4277.
OJT15D-5 & -5D TBO Escalation
Following the overhaul of several JT15D-5D engines as part of a sampling plan, P&WC has been approved by Transport Canada to increase the time between overhaul (TBO) from 3,000 to 3,500 hours. The new TBO interval is published in Service Bulletin 7003R29. Also, the JT15D-5 TBO has been increased from 3,500 to 3,600 hours.
For more info, contact Dan Arrick in BTL at 800.525.2376 or Jon Dodson in LNK at 800.228.4277.
Always Preload Your Torque Wrench
Preloading a torque wrench is an important process in overall accuracy of these tools. It must be performed each time the torque wrench is used after periods of non-use or whenever torque direction is changed. There are several reasons for preloading your torque wrench. First, it will set internal components so that when force is applied, torque begins immediately with no internal settling. Second, it distributes lubrication to moving internal parts. The final reason is the hysteresis characteristic of the steel, initial stress should be applied to the steel in order to moderate the hysteresis presence.
How to do it:
- Set torque wrench between 50% & 100% of full scale.
- Mount torque drive in a stationary fixture (i.e. socket welded to bench, vise).
- Exercise the torque wrench 3-5 times in the direction you will be verifying.
- Perform torque measurement.
Remember to store torque wrenches (Click-type) in the low setting. Otherwise calibration will be needed at shorter intervals.
Contact Duncan’s Calibrations Lab for additional info at 800.228.4277.
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