M20M gear failed to retract - then failed to extend (initially)

[Rick Junkin]

I originally posted this in the Mooney Bravo forum yesterday, but realized that the info may be useful to a broader audience and I may have a better chance of getting answers to my questions.

Sharing this morning's experience "just in case it happens to you".

This did NOT end with a gear-up landing. I have a couple of questions about some of the details of the event though. Bottom line up front - one of the links on the inside gear door for my right main became disconnected and the door didn't operate properly, preventing the right main from fully retracting.  Here's what happened:

I got a GEAR UNSAFE light, confirmed with an unsafe indication on the floor indicator, shortly after raising the gear switch on takeoff this morning. The GEAR ACTUATOR circuit breaker was also popped. I got into the checklist. I didn't know what position any of my gear were in at this point.

Question #1: Is there a checklist for this scenario? It doesn't fit the GEAR FAILS TO RETRACT - GEAR HORN DOES NOT SOUND checklist because the ACTUATOR breaker popped, not the RELAY breaker. And continuing the flight certainly wouldn't have been a good idea with the failure that I had.

After not finding what I needed in the checklist, I started troubleshooting with the goal of getting the gear indicating down and locked. I tried resetting the ACTUATOR circuit breaker with the gear handle up, and it popped immediately as expected. I put the gear handle down and reset the circuit breaker. It didn't pop, but nothing moved and the GEAR UNSAFE light remained illuminated and the floor indicator showed unsafe. So I pulled the circuit breaker.

Next step was to attempt an emergency extension using the checklist. The emergency extension clutch didn't feel like it engaged. I pulled the T handle about 40 times with no success. I stowed the T handle and the secured the emergency gear lever.

Question #2: Is it to be expected that the emergency extension clutch won't engage if the mains are out of sequence? I didn't know they were out of sequence at this time, but this could be an indication that they are, which is helpful information if you don't have a tower to fly by for a look.

I called the tower for a fly-by to look at my gear, and they cleared me for pattern entry and a low approach. Tower was able to tell me on downwind that they could see that my right main was slightly extended. I declared the emergency at that point and ran through other ideas for getting the gear down, while also considering where to land if I couldn't. I had 2 hours worth of fuel to figure it out and let the airport get prepared to clear my airplane from the runway after the gear-up landing.

Question #3: Is there any advantage to consider a belly landing in the grass vs the runway? I was going to use the runway with my gear configuration, figuring it likely that the right main would dig in on the grass and complicate things. Either way I think you get to replace the bottom of the airplane and anything else that catches.

At this point I had the ACTUATOR circuit breaker pulled, gear switch down, and the emergency extension lever stowed and latched. I put some G on the airplane while resetting the ACTUATOR circuit breaker and immediately heard the gear motor running. GEAR SAFE light and floor indication followed shortly after. I don't believe our POH suggests putting G on the airplane to help extend the gear, but its a procedure in another airplane I fly so I gave it a shot. And it worked.

I advised the tower and asked for clearance to land. It worked out ok, but in retrospect that wasn't the best decision. I should have executed the tower fly-by so that they could take a closer look and let me know if I had any damage or other weirdness. I had plenty of fuel.

Epilogue: This incident was precipitated by a fastener on a gear door connecting rod failing/coming loose. This particular door is closed on the ground and the only way to preflight the fasteners on the connecting rods is to climb under the airplane and stick your head up into the wheel well with a flashlight, not something that I have routinely done in the past. I'm going to add it to my oil change ritual, easy to do while I'm under there checking tire pressures. Incidentally, the door felt secure on my "grab test" during preflight. There was some minor deformation done to the door that looks repairable, but my IA will tell me for sure tomorrow. Either way, sure beats a gear-up landing.

Cheers,
Rick

 

 

[markejackson02]

Well done.

 

[TCC]

Great job. Adding Gs to help Mother Nature out was smart. Just to get an idea of troubleshooting vs fuel remaining, how long was the overall flight?

[Rick Junkin]

5 minutes ago, TCC said:

Great job. Adding Gs to help Mother Nature out was smart. Just to get an idea of troubleshooting vs fuel remaining, how long was the overall flight?

Thanks! I was airborne for about 15 minutes. It was a 0.7 including ground time according to Foreflight. I burned a total of 5.1 gallons of the 32g on board, throttled back to 20/2200 to stay under gear retraction speed (a conservative decision).

Cheers,
Rick
 

[thinwing]

Hard to tell by pic..but that rod hanging down is failed part?I assume under air load that door would be jammed closed with gear retracting on top of it ,thus stalling the moter and blowing the fuse...

[Rick Junkin]

30 minutes ago, thinwing said:

Hard to tell by pic..but that rod hanging down is failed part?I assume under air load that door would be jammed closed with gear retracting on top of it ,thus stalling the moter and blowing the fuse...

Technically the clevis pin that holds that connecting rod to the rest of the gear door mechanism is what failed, but I believe your assessment could be correct. Judging from the deformation of the door, it appears that the connecting rod fell free when the clevis pin failed and the inner door partially closed against it. It could be that the wheel retracted against the closed door, as you said, but there aren't any witness marks on the door from the wheel or tire.

However, since the nose and left main were fully retracted, and the gear all move symmetrically (I think?) as they're driven by a single actuator, it could be that the right main wheel was mostly in the well with the inner door partially closed over it but being held open by the dangling connecting rod.  The outer door may have been binding against the open inner door just enough to keep the gear from reaching its up limit switch, which could have caused the actuator to continue running, jam the drive train and stall, and pop the breaker. I didn't get to talk to the tower controller afterwards to ask exactly what he saw (my call went to voice mail, unfortunately), so its possible he was just seeing the doors partially open, but I don't want to assume anything at this point. If I have the time I'll take a closer look at all of the pieces and parts and see if I can determine exactly what happened.

Or, more likely, I'll have a glass of Woodford and just be happy that the gear finally came down. The details of anything before that, other than the failed clevis pin that caused it all, now seem somehow unimportant...

Cheers,
Rick

 

[thinwing]

hey Rick have a second Woodfords on me...a great job all arround....Clevis pins for are so simple...held in by simple cotter pin...of course they need to be installed correctly..k

[kortopates]

On 7/24/2017 at 7:14 AM, Junkman said:

Next step was to attempt an emergency extension using the checklist. The emergency extension clutch didn't feel like it engaged. I pulled the T handle about 40 times with no success. I stowed the T handle and the secured the emergency gear lever.

Question #2: Is it to be expected that the emergency extension clutch won't engage if the mains are out of sequence? I didn't know they were out of sequence at this time, but this could be an indication that they are, which is helpful information if you don't have a tower to fly by for a look.

The emergency extension clutch should work in any gear position. Since it apparently did not engage, the brass clutch must be chewed up from attempting to raise the gear with the emergency gear lever unsecured - that is the only way I know of how that they get chewed up unless the rigging is seriously off. But this an annual checklist item when performing the gear checks. The gear pre-load checks are done after manually extending the gear, not using the electric motor. Thus this should have been tested good at the last annual whenever that was.

Very odd your clevis pin fell out. Much more common is those links break at the hole. First the hole wears larger from operating the gear at or above max gear extension speed. As the holes enlarge so does that shock on them each time the gear is lowered, till they break at the hole. They can be repaired by welding the hole smaller and then punching the proper hole size back out to a nice tight fit around the clevis pin. Somehow, the cotter pin securing the clevis pin became damaged enough that what was left of it must have fell out - they just don't break. You should check, but my guess is the hole in the rod has worn enlarged enough that the clevis pin fit was sloppy enough that the cotter pin got worked to failure till the pin fell off.  Only point of all this is if the clevis pin fits sloppily into the rod link hole you'll need to replace or repair the link or you'll see this happen again very soon. Any slop you find on the right side probably also exist on the left side too; so suggest checking them all on both sides.

[Rick Junkin]

4 minutes ago, kortopates said:

 Only point of all this is if the clevis pin fits sloppily into the rod link hole you'll need to replace or repair the link or you'll see this happen again very soon. Any slop you find on the right side probably also exist on the left side too; so suggest checking them all on both sides.

Thanks, we'll take a close look at the holes for wear.

Cheers,
Rick

[Rick Junkin]

7 minutes ago, kortopates said:

The emergency extension clutch should work in any gear position. Since it apparently did not engage, the brass clutch must be chewed up from attempting to raise the gear with the emergency gear lever unsecured - that is the only way I know of how that they get chewed up unless the rigging is seriously off. But this an annual checklist item when performing the gear checks. The gear pre-load checks are done after manually extending the gear, not using the electric motor. Thus this should have been tested good at the last annual whenever that was.

I had my annual scheduled for next week, so we're going to go ahead and complete all of the 100 hour inspection items on the gear now before returning to service. I just had GAMIs installed and was hoping to get the first iteration of tuning completed before the annual (that's what I was planning to do on the IFE sortie), but it sounds like I may have an issue that will keep the airplane grounded for a bit. Thanks for the info!

Cheers,
Rick

[kortopates]

4 minutes ago, Junkman said:

I had my annual scheduled for next week, so we're going to go ahead and complete all of the 100 hour inspection items on the gear now before returning to service. I just had GAMIs installed and was hoping to get the first iteration of tuning completed before the annual (that's what I was planning to do on the IFE sortie), but it sounds like I may have an issue that will keep the airplane grounded for a bit. Thanks for the info!

Cheers,
Rick

Very good. I know I wouldn't want to fly it till I had the emergency gear extension repaired back to being airworthy either. Hopefully you'll just need some minor work to get back to working condition.

Take your time with the gami's. If you are new to doing gami sweeps it may take you a few flights to get good data. Getting good data in turbo's is harder to get good data than normally aspirated engines. Most pilots learning perform the sweeps too quickly which doesn't work too well. You need to be able to see that your results are very repeatable or consistent. Then you can trust your data to make some changes. Be sure to include the LOP Mag test too because ignition issues will also lead to roughness issues and can even prevent getting good gami spreads. Suggest following our process at http://content.savvyanalysis.com/static/pdf/SavvyAnalysisFlightTestProfiles.pdf to help you get good data. But you'll need fuel flow sensing on your monitor to be able to collect gami sweeps - trying to record it manually introduces way too much error.

Good luck.

[Rick Junkin]

I don't have fuel flow on my EDM 700, but I've developed a method of establishing a stable fuel flow for about a minute, record the time and FF, and then move to the next 0.2gph FF increment. I match those time tagged fuel flows to the nicely stair-stepped temperature data that I download from the 700. Takes me about 20-25 minutes to go from 15gph to 11.4gph where the engine gets rough. That was at 65% with the stock injectors, gave me a 0.8gph spread. Looking forward to narrowing that significantly.

Cheers,
Rick


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[Rick Junkin]

Lesson learned about the landing gear - If you ever have an asymmetric gear configuration caused by interference with one of the gear, something is now probably bent in the belly of the airplane. In my case its the right hand bell crank and the right hand gear extension push tube.

Tom, my mechanic, repaired the gear door linkage and we did a gear swing - the right main still would not fully retract, but the left main and the nose were fine. He dropped the belly panels and discovered that the right main push tube and bell crank were both bent. It all makes sense to me now. The single gear actuator moves all three gear symmetrically, so if that symmetry is disturbed, something has to give. When my right main bound up on retraction, the actuator continued to drive the retraction mechanism, so the push rod and the bellcrank deformed to absorb the travel that the wheel couldn't accomplish.

Straight-forward fix, now waiting on parts. I'm keeping a tally, will let y'all know what a failed cotter pin costs me...

And oh-by-the-way, yes, we replaced all of the clevis pins and cotter pins in the gear actuation system with new. And used stainless cotter pins.

On 7/25/2017 at 11:11 AM, kortopates said:

Very odd your clevis pin fell out. Much more common is those links break at the hole. First the hole wears larger from operating the gear at or above max gear extension speed. As the holes enlarge so does that shock on them each time the gear is lowered, till they break at the hole. They can be repaired by welding the hole smaller and then punching the proper hole size back out to a nice tight fit around the clevis pin. Somehow, the cotter pin securing the clevis pin became damaged enough that what was left of it must have fell out - they just don't break. You should check, but my guess is the hole in the rod has worn enlarged enough that the clevis pin fit was sloppy enough that the cotter pin got worked to failure till the pin fell off.  Only point of all this is if the clevis pin fits sloppily into the rod link hole you'll need to replace or repair the link or you'll see this happen again very soon. Any slop you find on the right side probably also exist on the left side too; so suggest checking them all on both sides.

The new clevis pin fit tightly into the holes on the bell crank and link, so we believe that the cotter pin had probably been gone for some time before the pin worked itself out. There was evidence of some minor corrosion, so that could be what got the cotter pin. We recovered both the original clevis pin and washer from the disconnected joint. The remains of the cotter pin were not found. I expect my new inspection routine will give me a better chance of catching something like this in the future before it can cause a bigger problem.

Cheers,
Rick

 

[Guest paulie]

A tower fly by isn't going to tell you anything and is dangerous.A in flight look is even worse. There was a mid air between a helo and fixed wing doing just that. A better idea would be mirrors that allow you to see the gear.

[Bennett]

A tower fly by isn't going to tell you anything and is dangerous.A in flight look is even worse. There was a mid air between a helo and fixed wing doing just that. A better idea would be mirrors that allow you to see the gear.

I've flown tower fly-bys on two occasions where I had concerns about the gear being down. Once in a Beech Sierra where I could not get 3 green lights in the panel (proved to be a defective micro switch on one main gear), and in my current Mooney that had a bent gear rod after retraction, and I had to recycle the gear several times) In neither case was this this a dangerous maneuver. I flew down the runway at about tower height, and at normal pattern speed. The tower staff used binoculars and reported that all three gear were down, and appeared normal. In each case I went around the pattern and landed as smoothly and slowly as I could. The fire truck stood by, and in neither case was there a collapse. Letting the tower know there was a potential problem, and soliciting their help in observing the gear, put notice to the rescue unit to stand by, and the tower staff to give me Priority in landing with plenty of space from other aircraft. I do agree that air to air observation can be dangerous without formation flying experience.

 

 

 

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[Rick Junkin]

57 minutes ago, paulie said:

A tower fly by isn't going to tell you anything and is dangerous.A in flight look is even worse. There was a mid air between a helo and fixed wing doing just that. A better idea would be mirrors that allow you to see the gear.

A pilot without the training, experience, and proficiency should not participate solo in formation flying. 

With the proper training, experience, and proficiency, there is nothing dangerous about executing tower fly-bys or formation flying as the risks are mitigated by the training/experience/proficiency.

Much can be gained from observation by a pair of eyes outside your cockpit, as was the case in this instance.

Cheers,
Rick

[Guest paulie]

I doubt that a guy with a pair of binoculars is going to be able to see if the gear is actually locked. 

[Rick Junkin]

22 minutes ago, paulie said:

I doubt that a guy with a pair of binoculars is going to be able to see if the gear is actually locked. 

There are useful things that a guy with a  pair of binoculars can tell you, such as one of your mains is partially extended. He can't positively tell you that everything's good, but he can definitely tell you that something doesn't look right. He can also tell you that your gear appear to be down, which is another piece of information you can use in your decision process as to what you're going to do next, and how you're going to do it.

More importantly, the original assertion that a tower fly-by is dangerous is incorrect. Its a tool that an appropriately prepared and skilled pilot can use to get more data about his airplane's configuration or condition. Calling it dangerous is misleading to someone who could otherwise add that tool to their troubleshooting kit by getting some training, experience, and proficiency.

Back on topic - Can anyone recommend a source for reasonably priced new parts? I have a request in to LASAR for a quote, and have located some "as removed" parts, but I'd like to compare pricing for new parts. I'm planning to call Duncan tomorrow. I'm specifically looking for 560202-502 BELLCRANK ASSEMBLY, RH and 560244-501 PUSH TUBE ASSEMBLY. Thanks for any point-outs.

Cheers,
Rick

[Guest paulie]

"Its a tool that an appropriately prepared and skilled pilot " That's true but what about the guy that flies 25-50 hours a year?  There were two accidents in Mooneys this week where the pilots managed to screw up landings and destroyed the airplanes.

I won't belabor this anymore. I think installing mirrors to view the gear would be a good idea.

[Rick Junkin]

Closing this out - final cost of a failed cotter pin in this particular instance is roughly $800 in parts and labor (completed in the course of doing the annual so I'm estimating) and, a surprise to me, providing the local FSDO all of the typical ramp check documentation, including statements from both me and my mechanic, that is requested when you declare an IFE as a GA pilot. I never had to do that in my previous life or day job, which admittedly is quite a different kind of flying.

I learned quite a bit from the experience, both about my airplane and about the FAA IFE after-action process for GA pilots. I had written another two paragraphs about some rethinking I've done for how I would handle a situation like this in the future, but suffice it to say that I'm happy that it all worked out well.

I'll also add an endorsement for subscribing to the AOPA Pilot Protection Service. I called them as soon as I got the voicemail from the local FSDO, and was connected to an aviation lawyer who gave me some good advice about the call I was about to make to the FSDO. He also reviewed and edited my written statement before I submitted it. It was reassuring to have the help of someone intimately familiar with the ins and outs of the process.

Cheers,
Rick

[kortopates]

Thanks for relaying the FSDO involvement. Just curious. Very seldom is a pilot investigated for declaring an emergency; even when the pilot uses his emergency authority under 91.3 to deviate from the FARs. And this sounds like you were contacted by an airworthiness inspector to investigate maintenance as it relates to the mechanical problem you had as opposed to your pilot actions. Please correct me if they weren't focused on the maintenance/mechanical side of it. My experience is that if there was no mechanical issue involved that they rarely contact you at all.

[Rick Junkin]

On 8/10/2017 at 10:53 AM, kortopates said:

Thanks for relaying the FSDO involvement. Just curious. Very seldom is a pilot investigated for declaring an emergency; even when the pilot uses his emergency authority under 91.3 to deviate from the FARs. And this sounds like you were contacted by an airworthiness inspector to investigate maintenance as it relates to the mechanical problem you had as opposed to your pilot actions. Please correct me if they weren't focused on the maintenance/mechanical side of it. My experience is that if there was no mechanical issue involved that they rarely contact you at all.

I'm not sure, Paul. The title of the gentleman from the FSDO is "Aviation Safety Inspector - General Aviation Unit". He didn't ask for a statement from my mechanic until after I had submitted my statement, along with all of the aircraft and engine  log book entries and my personal qualification documentation. If he was focused on the mechanical side, I would think he would have asked for the mechanic's statement up front? I read that the FAA has totally reorganized and taken away the FSDO's authority to provide interpretation of the CFRs at the local level, trying to drive consistency in the interpretation and application of the regulations. Maybe what I experienced is the new normal.

I need to add that he was very personable and easy to work with. There were no formal deadlines for submission, and he said that he needed the info to close out his "paperwork" for the incident. The AOPA attorney I talked to had told me to expect this, and to cooperate until anything appeared to escalate, at which point I was to give the attorney a call back. Its been several weeks since my last exchange with the FAA, so I think its been put to bed. I'm not gong to to call and ask...

Cheers,
Rick

 

[DonMuncy]

I almost hate to mention it, for fear that someone will be hesitant to declare an emergency, but from my last experience, they are getting a little more aggressive. After I had declared for a mechanical problem, the FAA called and asked for the A&P's name. The good news was that when they talked to him and he verified I had a failed vacuum pump and broken cylinder, and they did not do anything else.

[Rick Junkin]

3 hours ago, DonMuncy said:

I almost hate to mention it, for fear that someone will be hesitant to declare an emergency, but from my last experience, they are getting a little more aggressive. 

Like I said in an early post, I had written another two paragraphs about how I will do things differently "next time", then deleted them for this exact reason, Don (not wanting to dissuade anyone from asking for help in an emergency). I have a considerable amount of exposure to declaring emergencies in military aircraft, and was never hesitant to do so. I've changed my perspective on that after this experience. I can't and won't tell anyone else when it is and isn't appropriate to declare, but I have changed my personal criteria. I'm disappointed that I've been made to feel that I have to do that.

Cheers,
Rick

[kortopates]

On 8/28/2017 at 1:10 PM, Junkman said:

I'm not sure, Paul. The title of the gentleman from the FSDO is "Aviation Safety Inspector - General Aviation Unit". He didn't ask for a statement from my mechanic until after I had submitted my statement, along with all of the aircraft and engine  log book entries and my personal qualification documentation. If he was focused on the mechanical side, I would think he would have asked for the mechanic's statement up front? I read that the FAA has totally reorganized and taken away the FSDO's authority to provide interpretation of the CFRs at the local level, trying to drive consistency in the interpretation and application of the regulations. Maybe what I experienced is the new normal.

I need to add that he was very personable and easy to work with. There were no formal deadlines for submission, and he said that he needed the info to close out his "paperwork" for the incident. The AOPA attorney I talked to had told me to expect this, and to cooperate until anything appeared to escalate, at which point I was to give the attorney a call back. Its been several weeks since my last exchange with the FAA, so I think its been put to bed. I'm not gong to to call and ask...

Cheers,
Rick

Thanks for expanding and clarifying Rick. Unfortunately, "Aviation Safety Inspector - General Aviation Unit" doesn't tell us which of three types he may be. There are Airworthiness ASI's concerned with maintenance, Operations ASI's concerned with Pilots and Avionics ASI's. So your ASI could have been either Airworthiness or Ops based. I expect it would be normal to answer standard questions about pilot qualifications in any report they completed but so often as you know, the process doesn't go beyond a telephone call. And I surely don't know why this ASI needed to write a full report.  

The FAA does list a directory for their employees that sometime but not always list what kind of ASI they are. I assume you are in St Louis 03 FSDO with the directory being here: Saint Louis, Missouri - Flight Standards District Office - 03  If you browse that, perhaps you'll recognize the name and just maybe it will have his full title as to which kind of ASI he is.