Legacy Gear Retraction Problem - UPDATE!

A few days ago I posted a problem we were having with a Legacy gear swing on annual inspection. It was a chattering or shutter experienced as the right main retracted and interfaced with the inner gear door sequencing valve.

I would like to thank everyone that responded with helpful hints and suggestions via LML and off line.

With the help of a friend’s Legacy that is in the final phase of construction, we were able to “borrow” parts and expedite the trouble shooting.

For those still interested, here is what we found and what we did to trouble shoot this problem.

* Disconnected inner and outer gear doors - NO HELP.

* Rebuilt the right sequencing valve with new kit - NO HELP.

* Replaced the right sequencing valve with new - NO HELP.

* Adjusted the right sequencing valve from minimum to maximum - NO HELP.

* Adjusted the Hyd Pressure from less than a 1,000psi to 1,425psi - NO HELP.

* Overrode the high pressure shut off pressure switch momentarily - NO HELP.

* Isolated other gear to prioritize pressure to right gear - NO HELP.

* Found that by “helping” the right gear go up by hand, there was - NO CHATTERING.

* Suspected weak main gear actuator, replaced with new - NO HELP.

* Suspected possi ble problem with Hyd Power pack - replaced with new - NO HELP.

* Isolated inner gear door actuator AFTER the sequencing valve - NO CHATTERING.

* Suspected problem with inner gear door actuator - replaced - NO HELP.

At this point we were at a COMPLETE loss. Other than replace hydro lines, what else could we do?

Then one of the (many) able bodied by-standers who had some extensive experience with hydraulics, surmised that there is some sort of dynamic/harmonic going on between the inner gear door actuator and the sequencing valve. He suggested putting a reducer in the up side of the inner gear door actuator. Sounded strange, but at this point what did we have to loose. We tried the retraction and it worked PERFECTLY time after time!!

The only thing we haven’t done yet is connect the inner gear door, but watching the actuator move it is moving smoothly and in sequence, so we are “cautiously optimistic” that we have solved the problem.

Does anyone have an idea of what is going on here? What could change after two years to cause this problem? Is there anything wrong with a fix like this if everything is working well?

 

Thanks again to everyone at LML for the help and advice.

Erik Larson

Legacy

N74FX