Landing gear

[rmorris]

Have a new issue I need some advice in handling:

Plane is a 1968 Skymaster T337C, s/n 337-0775 Landing gear issue

When I cycle my landing gear up after t/o, it cycles all the way up, but the handle never returns to the neutral positon. After waiting a while, I can pull the handle down to neutral, and then the doors droop back down (verified by fly bys). I can then pump the emerg handle and secure up the gear doors.

I have had all the leaks tracked down and repaired, also put on all new hoses.

On the ground, attached to a mule, the gear cycles up and down with no issue. Handle kicks back down to neutral as expected.

In flight - When putting the gear down, it always cycles down and the handle kicks to neutral.

While the workaround, hand pumping the doors back closed after putting the handle into neutral manually, works - it is not desireable. But it is also not desireable to keep paying mechanics to hook up to their mules and say all is well with the gear system (has happened at several different shops now).

[hharney]

Robert

It was great to see you at OSH. Sorry about the misconfusion and I really do appreciate you talking to Cessna and bring the book over.

Craig and I will study the schematics in the next couple of days and let you know what might be happening with the gear scenario. Remember the guy with the 310 suggested a couple of things. Did you try them yet?

Cheers

[Skymaster337B]

The first thing that comes to my mind is that the resevior isn't full. At the expense of insulting you, have you confirmed the hydraulic resevior is full by adding 5606 until is pisses out of the vent?

The other things include adjusting the gear handle releases, replacing door solenoid, and worse case the hydraulic solenoid valve in the hydraulic power pack. I don't think it is the time delay valve because it either works or it doesn't...there's no adjustment for it.

[plane41]

With the ac on jacks, main gear doors disconnected and held up with bungee cords. Jack the wheels up while a person watches the main gear strut from behind the ac under aft engine looking forward. . Just when the main gear struts engage the up locks and the up locks are engaged. at this point your doors would normally close and the handle would return to neutral. But if the struts lift off the up locks, this opens the gear door close circuit with is also connected via the hyd pack to the handle return. The question is how much does the strut lift up. Just a little, its a good bet the problem is your up locks. If its a lot, say 1/2 inch, then its a bigger problem. in the gear down position, check each strut for proper seating in saddle. (see rigging and adjusting main gear). Make sure you also check the ac frame where the strut hits when in the up position. Any bends(even minor) allow the strut to lift pass the unlocks.

[rmorris]

Yes, the fluid was serviced until,it came out the overflow.

Will look at ore items and run that jack test where the doors are disconnected (hopefully this week) and report back with findings.

Thanks for the comments and suggestions.

[hharney]

If it was a pressure switch issue using the mule may change the pressure that would normally be seen with the engine driven pump. Make sure the pressure on the mule is correct based on engine pump. With my drill gun at least you eliminate this potential issue by actually using the aircraft system 100%.

[Tom]

I'm thinking it might be an internal leak in one of the actuators, or a weak pump output. The higher flow/pressure of the mule would mask either problem. Try setting the mule at progressivly higher pressures from the lowest setting. You might also want to put a direct reading guage in the system to look at pump pressure.