Landing gear dont "lock" in the up position reliably

[Bryan Bowlsbey]

I apologize if this is addressed anywhere on the forum; I cant seem to find a similar problem.

Narrative: The landing gear on my '59 180 has begun to have difficulty "locking" in the up position. On take off at full power and pitched for aprox. 96 mph I select "gear up" . The gear handle moves all the way to the floor, and then begins to bounce up and down about 1.5" while the "up" light continues to flash. No problems with electrical breakers, voltmeter doesn't indicate a weak battery, our mechanic went through and re-adjusted the up switches. The mechanic did indicate that the gear moves a lot freer when the push pull mechanism is detached which stands to reason. Replacing wiring harnesses, conduits, the transmission etc. would probably be a good idea since I think most of these things haven't been replaced since new.) The problem is intermittent, and so far when it occurs I have been able to eventually get a solid light by leveling out, throttling back, and cycling the gear down and back up several times. We have had the airplane on jacks and swung the gear twice in relation to this problem. There is a potential that the left brake line may be hitting against the gear door stop while flying, (it doesn't do so while on jacks).

I am concerned about just starting the swapping of expensive parts before I can figure out the "root cause" of the problem. I am hopping someone with a better understanding of the system can give me an idea where to continue troubleshooting. Appreciate any guidance or even speculation you may be able to provide.

[Jerry Jesion]

Bryan,
I had a similar problem with my 180 when I had the push/pull cables replaced last year. After take off I did not get the up light, and the breaker blew. I went back to the airport and selected down and when I reset the breaker the gear went down normally. The plane was put up on jacks and it cycled w/o a problem. The up limit switch was re-adjusted and it has worked fine since. Cliff Wilewski at surmised that there was some aerodynamic force on the gear system that changed the correct setting for the up switch.

What is happening to your plane sounds like the up limit switch might be mis-adjusted. I suggest that you call Cliff and ask his advice. He is an expert and a good guy!

Regards,
Jerry

[Gil Dahl]

BRYAN
Comanches do not have an up lock. they only have a brake on the gear transmission which is not "holding" in your case. The vibration at full power and gravity pull the gear down until the up limit switch closes and the motor runs the gear back up. Fix the brake before you burn up the motor.

Gil

[Bryan Bowlsbey]

OK, so with a the right words to search by, (piper, comanche, "gear transmission" and brake, thanks guys), I found the document at this link:
http://comanchegear.com/LANDING%20GEAR% ... %20svc.pdf

It seems to be a document that Matt from Comanche Gear pulled together from original Piper sources. Looks like I can ask the mechanic to adjust the brake. Think I will ask that they check all the bushings and common hardware that could be replaced while they are in there.

Is the brake solenoid actuated by the open limit switch?

[Gil Dahl]

Bryan
If you go to the PA 24 Service Manual on this web site, page 1 J 12 you will see a exploded view of the trans assembly. Item 17 is the brake solenoid and # 19 is the spring. The spring holds the brake "shoe" on and the solenoid lifts it off when 12 volts is applied to the motor. I will bet your spring has broken.
Gil

[Bryan Bowlsbey]

Will do. Thanks.

[Kristin Winter]

The brake sounds like the most likely problem, but I do wonder who old your bungees are, or if one has slipped off its roller. Bungees help to hold the gear up and there is a big difference between new bungees and two or three year old bungees. I change them annually. With a Bogert tool, it only takes about 30 minutes to change two and they only cost about $36 a pair. They help out the transmission and transmissions are expensive.

Kristin

[Bryan Bowlsbey]

New Bungees by our mechanic this past February, but I am not familiar enough yet to visually inspect to see if one has slipped. I'll add that to the list for the mechanic, and tag along to get smarter.

[N3322G]

Bryan,

I also have the bungees changed every year at annual.

You might consider attending the next CPPP course - you learn a lot - in the mean time, I suggest the Maurice Taylor DVDs http://www.comancheflyer.com/NS/hold/h1/cff_goodies.pdf

[Ray B]

And don't forget you can help out that old transmission with a little hand pressure on the gear handle as recommended in the old Piper POH's. ( That's an advantage the latter model Comanches don't have) Ray B

[Kristin Winter]

There is an access panel just behind the main gear strut behind which is the bungee and arm. Grab a creeper and an electic screwdriver and remove the panel and look. If the bungee is loose, it is off. You will be able to tell immediately.

Be sure to tell your mechanic that the bungee roller that is bolted to the arm is supposed to be free to turn.