Oil leak for pjvr99

[Dan Wilson]

Figured I would put this in a new thread to keep from causing too much thread creep on the TIT thread.

I had a similar problem on a check ride one day in Germany.

From beginning to end to worked like this.

At briefing an evaluator shows up for a no notice check ride (first indication of a really crappy day).

We flew to Zweibruken to pick up a squadron for a unit move to Bitburg (poor slobs were supposed to endure an 8 hour overwater for a free ride just down the street).

On take off first indication something was wrong is torque (indication) started just going nuts, I had seen that before and it was gremlins in the indicator, usually could be fixed by pulling the c/b for a couple of minutes and resetting the breaker.

When I move the evaluator out of the way to pull the c/b I caught oil pressure going nuts on that engine (#2) so I stopped what I was doing to see what the whole engine was doing. At this point every thing was normal except torque going nuts, zero pressure on the engine and zero to fifty bounce on the gearbox, oil low light on and quantity about two gallons.

This was all as the gear was just coming up, and we had the engine bagged by the time we had just cleared the departure end of the runway, the prop pretty much seized up during the shutdown (that was really really fun), so we cleaned up the shut down and went straight ahead to land at Bitburg. During the flight we scanned everything to see where the oil was and amazingly enough the engine was completely clean (or as clean as a Herk engine ever gets).

After we landed at Bitburg, it was still clean for about the next thirty minutes, then we got the oil leak, it started to slowly run out of the tail pipe and kept running for the next two hours as all ten gallons that went missing was found again, much to the fighter guys chagrin (seems like they don't like lots of oil running down the ramp).

What we reconstructed was (our best guess as you will) on takeoff run the main oil scavenge pump crapped out (or could have been both the pressure and scavenge pump assembly or lines for the scavenge oil). Torquemeter went nuts as oil filled the torquemeter housing and shorted out the pickups. Engine oil pressure may have zeroed in the initial failure or after loss of oil quantity, it happened too quick to tell. As quantity got lower we lost gearbox oil pressure and oil low light went on, then we shut down the mill and there it sat until after sitting on the ground long enough for it to start working it way through the seals and passages to run out the tailpipe for the next two hours.

No idea if your problem has anything to do with what happened to us but that was the only time I had ever seen a leak like that out the tail like you video shows.

Let us know what you find the cause of the leak to be when you find it.

Dan

[pjvr99]

This is the source of my problem in the vid .....

a.k.a. poppet valve in the main oil pump pressure regulator

Edited March 30, 2010 by pjvr99
getting fuels and oils mixed :-(

[Dan Wilson]

:eek:

I would have never suspected that causing your leak - WOW

Thanks

Dan

[pjvr99]

Believe me, it was the last thing I would suspect. However, a bit of a give-away

was the 30psi oil pressure at 900° TIT and 75° oil temp. My thoughts were tending

to a break/crack in the ADH front cover plate or a failure of the seal between the

pressure and scavenge sides of the pump ....... but that's how knowledge and

experience is accumulated