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Topic-icon NAVAJO CHIEFTAIN LANDING GEAR ISSUE

  • GREENWORKS CUSTOM
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1 month 16 hours ago #2117

Merry Christmas!! First time posting. Looking for advice on a landing gear issue with my navajo chieftain. Issue: Landing gear failed to extend so I did the emergency gear extension. Fluid in power pack was very low so I filled it. Now, during the pre-take off check of the "gear handle down" the handle will not come back to the neutral position. Mechanic on the field checked the filters (no metal found), primed the pumps, and raised the plane on jacks and cycled the gear using an aux hydralic pump. But still, with engines running, the gear handle will not come back to the neutral position. If anyone has advice, I would greatly appreciate your time and help! Thank you!

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3 weeks 6 days ago #2120

Hi Greenworks,
I've contacted our Navajo expert. She should weigh in soon.
I downloaded the MX manual and it appears that the problem could be related to low hyd system pressure when using engine pump pressure. Since the handle does release when using the hydraulic test "mule" but doesn't when pressure is supplied by the engine pumps, checking the system pressure (engine driven pump output pressure) does seem like a next step.
Kristin may know exactly where to go; she has operated and flown Navajos.
Pls let me know if you find the problem and what you did to solve it.
Thanks,
Steve

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3 weeks 6 days ago #2121

Thank you Steve!

I look forward to hearing from Kristin!

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3 weeks 5 days ago #2124

Hi! Kristin here! To whom am I typing?

I responded to a request from Kent, which may be from you originally.

I am thinking either pumps or internal leakage in the control pack. Lets start with cheaper first. I would recommend first doing the ground check with just one engine ruling. Test just running one side at a time. See if with one running engine, one side takes more pumps with the hand pump than the other. I am not sure they will learn anything, but it is cheap to try. I would then replace the lamest of the hydraulic pumps and try again. See if the new one works and the other doesn't. It may well be the power pack, but the cost of removing and overhauling them is fairly high, I would try the lower cost of overhauling one of the pumps first as it is much cheaper and easier to do. Exchange units should be available.

If installing a fresh hydraulic pump does not make it work just running the engine with the good pump, then you are looking at the hydraulic control pack. If a new pump does work, then get another new pump and you will be on you way.

I will monitor this thread more closely now that the holidays are almost over if I can be of further help.

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3 weeks 5 days ago #2125

Good Morning Kristin!

This is Paul. And yes, you had replied to me before! Thank you for your time!

To answer your question, I have tried the 'gear handle down' check with each engine individually and the result is the exact same. 14 pumps with the emergency gear handle in order to get the gear handle to move to the neutral position.

What I was hoping for was a test that could be done on the hydraulic pumps without taking them off. I just find it hard to believe that both pumps failed at the same time!

Again, thank you for your time and advice Kristin!

Sincerely,

Paul

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3 weeks 5 days ago #2126

Paul,

Given that both pumps are the same, then it seems more likely that you have an internal leakage in the control pack, though it is possible for both pumps to be failed as often pilots don't check them individually. This allows one to fail and the system run with only one working for an extended period of time.

I don't know if any easy way of testing the pump on the engine. I am sure that something could be rigged up, but the truth is that the labor expense of doing that would exceed the cost of replacing one of the pumps and testing again.

Kristin

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