Gear up landing of PA-24-250

[Chris Potalivo]

Unfortunately on the maiden flight (for me) the very first landing on N8166P was accomplished gear up. Working with the FAA but, can anyone think of a scenario that this fits in:
1. I know I pulled the gear handle down. My wife confirmed that she heard the gear start to cycle. This is our second Comanche and she has been flying with me for 20 years. I do not have a vivid memory nor my daughter of hearing the gear cycle.
2. In the middle of the GUMP I got distracted, I do not have a mental picture of the green light.
3. During the decent we were high and I was at idle power for most of the way down - with NO gear alarm
4. It was a perfect landing with minimal damage other than the obvious for a belly landing.
5. When the aircraft settled on the ground and after that horrendous screech of sound that I never want to hear, the Gear Alarm was blaring away. My wife claims she heard it as soon as the plane settled on the ground, my daughter and I heard it when the plane stopped. ALL concur that it was NOT on during the decent. Living in a mountainous area of Pennsylvania we are all aware of the alarm since we have to clear a ridge to land at our home airport, which means many times we are at a reduced power level prior to the gear coming down and the "infernal" alarm is blaring.
6. The FAA inspector found the gear handle down. One of the difference between this Comanche (1963) and my first (1958) is the gear switch which is a 3 position switch, up middle/off down versus up and down on the 58. Without confirmation of the green light it is conceivable that I only put the switch into the middle position and in my haste to exit the aircraft (it was filling with smoke), I could have hit the handle.
7. When the aircraft was on its belly (the front gear flush with the ground) the mains looked they were not deployed.
8. When they lifted the plane to pull up on a flat bed the gear dropped.
9. The FAA inspector found that the gear breaker was tripped. He also inspected the manual over-ride and noted that the decoupling lever on the worm gear was at about a 20 to 25 degree angle from the worm gear versus flat. He asked if that was normal, I could not answer him. The handle did move with the gear.
10. The plane was sitting on 4 tires when the FAA guy cycled the gear after resetting the breaker. The gear went down about 5 inches and hit the ground. He then cycled the gear back up. He did this about 2 or 3 times. Neither time did the breaker trip. From his initial perspective it appears the gear works.
11. The last log entry for maintenance shows they performed the gear inspection AD. which consisted of new bungee's, the side brace inspection, as well as a new gear motor. There was one landing after the AD/maintenance was performed.

Any help would be appreciated. I am not so much concerned with the FAA, rather trying to figure out what set of circumstances would derive the above scenario. I wish to God I could remember seeing the green light come on.

[N3322G]

Chris,

I'm so sorry to hear of the problem. Your situation sounds different but this may help. It runs 5 pages http://www.comancheflyer.com/forum2/vie ... ested+blog

I would suggest calling Matt Kurke at www.comanchegear.com

Again, you have my sympathies, whatever the outcome.

[Kristin Winter]

I have heard of the breaker popping when the gear is near the end of the retraction cycle and then the pilot putting the gear switch down and of course the gear does not come down. Sometimes we see what we expect to see, and that includes seeing a green light.

When the fed run your gear down after the accident and it hit part way extended, he probably damaged the system further. He may well have trashed the conduits and even caused the transmission to rip out of its moorings. Very bad form for him to do that.

[James Turner]

Hi Chris. Sorry to hear about your mishap.

It sounds like a lot of things happened but I had an instance where the CB tripped half way through the gear retraction cycle. My problem was due in part to the motor that had partially fried itself causing it to pull ridiculous amps and tripping the breaker. That said, the root cause of the problem was likely my gear conduits which are old and in need of replacement. Over time I think the motor was straining against the conduits and eventually gave out.

Regarding the gear warning horn; if you have a look at the micro switch you'll see how crudely it is adjusted and it is not outside the bounds of reason that due to a small adjustment problem it wasn't actuating correctly until the impact of the landing.

Having the FAA inspector actuate the gear and allow it to strike the ground mid travel seems like an awful abuse of the system and will likely have masked any bent conduit or transmission issue as they will be damaged for sure now.

Hope you get to the bottom of it.

James.

[Andrew Conroy]

I would like to add possible speculation. Imagine that the emergency release lever is disengaged. Could the gear mechanism have become jammed as the retract motor actuator moved aft? Or if the gear is disengaged, the retract motor will run continuously eventually binding the jack screw. There isn't a lot holding the forward actuator end in place and I could see the release handle getting cought on something, thus popping the breaker.

Do you remember what position the manual extension telescoping lever was in before touchdown? If my assumption is correct, the gear was mostly down but might have been hanging to just before the over center linkages could hold the hear down. I bet the lever wasn't fully forward. But might have been pointing up and slightly aft.



I had a similar experience as the pre-buy for my ship was done in my hangar. When the PO demonstrated the emergency gear test, he didn't reset it properly. When I came home from sea a month later, I took off in the plane for the first time my gear got all jammed up on my lopresti nose doors. Gear froze half way up Forced to use the emergency extension. Nose gear doors were jamed tight against the main gear.


I advise anyone not familiar with the emergency extension procedure to practice it ON JACKS and reset the gear BY THE BOOK with someone who is competent and knows what to do.


Sorry to hear this happening to you. Let us know how this turns out.

[Hank Spellman]

For years, my practice when lowering the gear in my 1959 250 has been to move my right hand immediately from the gear switch to the emergency extension handle to follow it through its travel. At the same time, I keep a very light pressure on the left rudder pedal so I can feel the nose wheel steering engage at the last little bit of the nose gear travel. Then I extend the emergency handle to its full extension to check the distance from the top of the handle (just over a finger width on my airplane) and say out loud, "Mechanical check OK." Next, I check for the green light and say out loud, "Gear light green, landing gear down and locked."

My wife knows, and anyone else who is in the right seat is so instructed during the preflight briefing, to immediately inform me in no uncertain terms, if I fail to do those two call outs.

This procedure (my procedures, not the right seat occupant) has saved me from two belly slides because of electrical problems.

Hank
Henry A. Spellman