Emergency Gear Release

[William Hughes]

So, after all this discussion over the last few months, and the essential re-construction of the landing gear, I took CF-NZB up for my first flight after paying the bills. Far more money was spent that was reasonable but I still think its worth it. It had gone up for a check flight on the 19th of November but I had to go work, it had been in the paint shop, it rains on the west coast, and so on and so forth.

Anyways, I took it out and ran it at various altitudes and settings, recording the numbers and fuel flows to check against the charts later, and then went to do some circuits. I was hoping to practice several 65-70 knot approaches to touchdown. Weather was calm, +12, and overcast at 22,000 feet. A really nice day.

On my first circuit when I pushed in the throttle the rpm would not go over about 2400. Plane flew great and jumped up, but it did have my attention. Manifold pressure was fine so it wasn't ice and I had the carb heat on during descent. I got the plane cleaned up and on downwind (very little time for that, it is an impressive aircraft) and selected gear down. Nothing. No movement. Amber light is out, gear handle is on the floor. So not up and not down and not moving.

I got out of the circuit and off by myself, with various people on the radio suggesting various things, which I didn't expect and found distracting. The tower shut them up. Anyways, I ran through the checks, starting with circuit breakers. I think they were popped, but I couldn't tell, because the side wall trim was covering them! After a bit of prying and groping while keeping the plane out of the weeds, I got them pushed in (I think), and tried the gear. Nothing. No down, no up, no movement.

There was no rush. I had about 5 hours of fuel in the aircraft and it was a nice morning. I flew around in a circle and thought about it. Tried the breaker again - it was for certain in, cool, and the motor wasn't hot, and there was no electrical smell, and the gear switch did nothing.

So I gave that up and lowered the gear using the manual procedure, which worked great, and I was quite oddly pleased with the new placard riveted on the underside of the door cover. Latch came up easily, the gear dropped smoothly, and with a bit of muscle the lever came up and into place very smoothly and with a nice thunk. The green light was extremely comforting.

I took it to the home airfield (six minutes away) and landed completely without incident. It was a very very smooth slow landing and a wide wide turn into my tie-down space.

I am first in line to the shop tomorrow. I can't help but think about the squat switch or wiring. They just installed the Comanche Gear wiring harness, and we mutually inspected it per the manual and it was as per illustrations. They actually did a very neat and by the book job and charged me accordingly. The whole system was just dead - the motor didn't twitch at all. The mechanical components were not jammed at all and moved very freely.

Will update in a few days.

[N3322G]

Glad you kept your head and handled the emergency well. Very smart to realize how much time you had and to relax as much as possible when you have to do this stuff.

Looking forward to hearing what happened from the RPMs to the gear to the covered breakers.

If possible, you might want to engage Matt Kurke on the gear stuff. I'm sure you'll be putting it on jacks and personally checking the gear operations per the service manual. If you don't have a service manual, it is online under the tech tab. I always like it that as much experience as Clifton Aero has - they always have the service manual and the parts manual on the table next to the plane when they are doing the annual. Hope your shop does also.

[Michael Bryant]

A great point was made here regarding dealing with emergencies.

The airlines teach that the pilot who is flying determines how the emergency will be dealt with. That means deciding who will fly/communicate, and who will work the problem. In addition, I was taught to brief where (area and altitude) we work the problem, the current fuel status, and how long (time AND minimum fuel) we would work the problem before heading back to the airport for landing. We are also taught to use all available resources (other pilots on board, company operations and/or maintenance, ATC, etc.).

Obviously if you are by yourself, everything will rest on your shoulders, but it is still a good idea to verbalize the briefing. Convert the fuel remaining into time aloft and allow a cushion to get get back to there airport and land with small reserves. Set an alarm if you have one. Make sure to throttle back and lean if needed. It might surprise you how much time you have to work the problem. Take your time and carefully run the checklist.

Use all resources YOU have available. Declare an emergency, ATC will then make you a priority. If you are not alone, assign a passenger to keep their eyes outside looking for traffic and terrain while you work the problem. Also have them keep an eye on the clock. If you have another pilot, have them fly while you work the problem. Whether alone or not, if the checklist does not solve the problem, you could have the local FBO place a call to your mechanic for suggestions. Have the FBO ask their mechanic for ideas. You could also solicit ideas from other pilots and/or ATC. Finally, just in case, ask for the equipment as a precaution when you land. After landing, you can then let tower know if you do not need the equipment any longer.

I have had several gear extension problems in my flying career. With my first, after completing the alternate gear extension checklist unsuccessfully, I ,like William, received numerous suggestions from other pilots, most not helpful at all (like run the alternate gear extension checklist). I declared an emergency and used ATC to check my gear visually during a flyby, then had them give me an area to work my problem and asked them to help me keep an eye out for traffic. I called the FBO at my destination on my #2 radio and had them call my company for ideas as I had hours of fuel available. I tried everything they suggested and nothing worked. It would have been extremely embarrassing though, to have not called and not have thought of something which might have worked (after burning off all my fuel, I wound up making a gear up landing, caused be a failed microswitch which left the gear motor running at full speed when the gear hit the top of the wheel well breaking the welds in the gear box causing it to shift, making ANY gear extension impossible!).


William, congrats on handling the situation well and good luck with the trouble shooting!

Michael

[William Hughes]

Well, it is possibly the worst outcome. The aircraft went up on jacks, the position of the transmission and jack-screw were measured, and then everything was reset.

And then it all proceeded to work perfectly. Many gear swings and all in perfect order. Dang. I was really hoping for something obvious.

About the only thing we have left is suspecting the limit switch that shuts off the gear when up. The gear system was PAST where the switch cuts out. So that implies the switch failed to shut it off, jammed the screw, and then popped the breaker. The trim panel covering the breakers up probably meant that I hadn't *really* reset it. And even if I had it would have just popped again. Or the switch failed open, and magically fixed itself. There appears to be nothing wrong with it. I am left wondering if perhaps the person sitting in the left hand chair screwed up somehow? How the heck could I have managed to fail to put the gear down using the gear selector switch?

So, they are going to clean everything and very carefully reset the limit switch travel in the transmission per the specs. That did not get touched - we only really re-rigged the gear switches and the squat switch, the gear doors, and the gear itself. Perhaps the gear travel changed enough during all the work that it stressed where the limit switch was and caused the trouble.

We had a good discussion on how much force should be needed to flip the small red handle up to disengage the gear, and agreed that it should be easier than it is currently per some discussion on other threads. They will swing it a bunch more times and see if they can recreate it, and then reset the limit switch and we'll see what happens.

[Kristin Winter]

If I follow this correctly, I would suggest you replace the up limit switch. Matt Kurke at ComancheGear has them. Might as well eliminate that possible failure point.

[Hank Spellman]

Do not fret over the switch now appearing to work correctly. You would never completely trust that particular switch again. And an occasional misoperation is the first sign of an impending full failure.

Just a year ago, the squat switch failed on my airplane. The gear would not retract, which, if you are going to have a gear failure, is the best kind to have. Fortunately, Webco was on the direct route home. Unfortunately, I was just off of Dalhart, TX, and Webco is a long way from Dalhart at 140 indicated.

The next morning, Bob Weber and crew went to work immediately, and I was back in the air on the way home just after lunch.

I took the bad switch home just to test it out. After hooking it up to the multimeter to see what it was doing, it would not operate. But after about 10 tries, it started working again. Then it went into the trash. I didn't want that particular switch on my airplane ever again. After 55 years of operation, I think it had served its purpose.

Hank
Henry A. Spellman

[William Hughes]

At the moment, it appears the gear didn't make it all the way up. After a few cycles, they found a brand new brake line curling up and jamming between the gear and a bracket. The bracket was twisted and torn, and the brake line severely scuffed. On that particular cycle I figure it got badly jammed and then it popped the breaker. Luckily it went down - it was only jammed going up. Also luckily I still had brakes.

After that, I figure the rest of it was me scrabbling and attempting to reach around the side panel trim that was incorrectly installed over the breaker, so I didn't manage to reset it, or what have you.

The prop vernier handle was worn and if you just push it in to the panel, it pops back out two teeth, or about 150 rpm. You need to twist it about three turns to get it to actually go in all the way and hold, plus there is about a turn and a half of slack when switching from up to down.

All told a very interesting situation.

[Charles Schefer]

William, I add my complements on your handling the emergency - well done.

Regarding your brake line routing issue take a look at the pics Matt Kurke has on his Comanche Gear website. There are some great pics there of the proper brake line routing. I did a big gear overhaul project in early 2014. It took me 5 months and I learned a great deal about the gear system thanks to support by many in the ICS. One thing I learned regarding brake lines is that the line routing on the left and right main gear is NOT the same.

I've seen many, many comanches were the lines are routed identically (including mine when I bought it) and that is actually not correct. Matt has some great pics and I recommend checking them out to ensure the brake lines (and wires for that matter) are routed correctly so there is no interference when raising and lowering the gear.

Michael, thanks for the great comments on Air Carrier SOPs - great advice to be applied.

Best Regards,

- Charles

[Timothy Poole]

We just went through a similar situation with our PA-30. The gear would retract and then pop the circuit breaker. Upon investigation we found that the up limit switch was not being fully engaged. After several small adjustments to get the position re-rigged properly the gear is operating properly again.

As you did, our instructor ended up doing a manual gear extension to get the gear down and bring the aircraft back to the airport.

Tim

[N3322G]

In the past had an up limit switch problem - waited for the circuit breaker to cool, slowed to 105, put gear selector in down position, pushed in circuit breaker and gear lowered normally with a green gear light. Uneventful, low stress landing.

This is part of the Emergency Procedures in the Handbook developed by Zach Grant. It may also be in POH, not sure.

[William Hughes]

All is well. Took it out on the first available good weather day and made skid marks all over the place. No problems at all.

Made sure I had a good look at the circuit breakers first and checked them out by feel to ensure I knew what "normal" felt like. I also made sure that the gear up light was as bright as possible. There is certainly some component of pilot error likely in this sequence of events. If I had checked these items before the last flight, part of the incident would not have happened. It turns out that when they did the AD for changing the motor circuit breaker, the new breaker is at a different height than all the others. So when I was attempting to feel it behind the upholstery that was installed over it, I couldn't compare it to the others, and I had no idea of what "normal" was, anyway. Now I do. I also added this to the checklist.

I chose to not replace the limit switch. I had no *proof* that it was the culprit and I was reluctant to replace something that might be fine. It was clean, actuated properly, and made contact every single time. I have in the past, on other machinery, replaced components that didn't need to be and have introduced more trouble than I had started with, and I thought that this was a good candidate for leaving well enough alone. I know what you mean about never really trusting it again, though...

So, in short, the brake line was re-routed, and the limit switch was adjusted so that the release handle was not so stiff. Someone commented on a different post I made that the little release handle should be easy to move, and now it is.

Thanks for everyone's suggestions and help. It is very nice to have so much experience on tap!