Gear Issues 337B

wslade2 · #1 12-13-21, 12:15 AM

You can ground test each pump by observing system performance rear engine only and then front engine only running.

Also as I recall, manual recommends 3 cycles of gear after service on jackstands to be sure air is out.

I also rebuilt front actuator and had to top off multiple times.

You can also run the pumps while on jackstands using a drill. Splined socket from harbor freight fits the pump shaft.

While looking at that front wheel well area there other actuator in there that can leak, the uplock actuator and main gear actuator. If one is leaking, the others may be in same shape too.

To prime the pumps, I filled them manually while turning the prop. I put a hose on the power pack exterior vent and blew on it while cracking the suction line at each pump. Don’t run the pumps dry and unprimed. It’ll ruin the seals and you’ll have to start all over again. (Ask me how I know.)

Jhogan0101 · #2 12-13-21, 03:20 PM

Ok thanks for the info wslade2, we’ll try the things you mentioned. Hopefully thats it.

Jhogan0101 · #3 12-14-21, 11:40 AM

Update:

When front engine only running handle/doors behave normal

When rear engine only running, doors will open/close slow. Handle will not snap back to neutral.

Check valves were opened/cleaned no debris.

Swapping hydraulic pumps (front with rear)today to see if problem follows pump

Jhogan0101 · #4 12-14-21, 07:26 PM

Problem solved:

Rear intake/return fitting on rear pump was loose. The nut holding the o ring was not tight. The pump was sucking in air and mixing it with hydraulic fluid. We replaced the o ring and resealed. Crisis averted.

https://youtube.com/shorts/VsAM1Hqdw9Y?feature=share

wslade2 · #5 12-14-21, 08:34 PM

Awesome! Cheap and easy. How did it get loose? Not tightened enough first time? Or aging of the o-ring and back up ring made it loose compression/tightness. Maybe a prophylactic front o-ring change due too?

In the video....is that fitting not exactly straight and lined up or is that just an illusion? Could that be contributing to the initial failure? Doesn’t look like the compression nut is completely flat. Might just be my imagination not seeing it in person.

Jhogan0101 · #6 12-14-21, 08:43 PM

I think illusion, definitely wasn't cross threaded when removed. I think the nut got loose overtime, hoses were replaced in 2019 annual, possibly wasnt tightened down 100%. That Annual was 85 hours ago, noticed gear slowing down maybe 15 hours ago. But yeah, im glad its an easy problem to fix and didnt lead to a catastrophe. Thanks for your help with this.

Have a Merry Christmas and a Happy New Year!