Duncan Aviation logo

PW306C/PW306B Engine Oil Leaks

September 2010

I recently ran across an issue with an oil leak on a Pratt & Whitney engine and felt it would be to everyone’s benefit to clarify my findings.

With the top cowl off, the oil leak was evident at the top of the intermediate case and running down the side. A possible source is the speed (N1) sensor wiring harness assembly. In the PW306B & PW306C engine, the speed sensor is behind the fan and inside the #1 bearing cavity. A harness is then connected to the two speed sensors and fed through the intermediate case via the #1 bearing oil vent line. At the top, two gaskets sandwich the harness canister while the vent line continues on to the oil filler neck.

The speed sensor cover plate and electrical connector potting holes can leak oil. Per SB 25369, the fix is to install a new and improved speed sensor harness and new gaskets. The problem is the fan needs to come off and there is no commercial support program providing labor support from P&W at this time.   

If you have a PW 306A engine on your Gulfstream, the speed sensor is in the opposite end of the engine.


Bill Walker
Walker, Bill - Engine Tech Rep - Battle Creek, MI (BTL). Aviation professional since 1979.

Airframes: Astra, Challenger, Citation, Embraer, Falcon, Gulfstream, Hawker, Learjet, King Air, Global, Westwind

Engines: CF34, JT15D, PT6A Turboprop, 617F-E, PW300, PW500, PW600

Direct: +1 269.969.8486
Mobile: +1 269.317.5526


William Walker Engine Tech Rep Astra, Challenger, Citation, Embraer, Falcon, Global, Gulfstream, Hawker, King Air, Learjet, Westwind Battle Creek, MI (BTL) +1 269.969.8486

Related Tech Articles

What Are The Honeywell TFE731 Inspection Intervals For New And Classic Engines?
November 2023

Honeywell Issues Service Bulletin For Painting of Bypass Ducts
July 2023

Gulfstream GIV: Troubleshooting High Engine RPMs
March 2023

Another Option To Complete Honeywell Service Bulletin Before Deadline
January 2023

Deadline Approaching For The ECU Update For Honeywell HTF7000 Engines on Challenger 300
July 2023

View All Engine & APU Tech Articles