Mooney 231 possible gear actuator damage

[warrennn]

I have owned a Mooney 231 for about 23 years and had an unfortunate experience last Sunday when taking off from a field with a surface temperature of 100 degrees. The gear would not retract -- each time I tried (about 6 times in all) the gear extension breaker popped. I had assumed that the high temperature at the field caused the problem and flew home with a lowered landing gear.

 

I own a maintenance manual and soon discovered that the problem was likely the accidental unlatching of the mechanical gear extension system. I confirmed this by looking at the manual engage handle and discovered that it was indeed unlatched. The service manual recommends reattaching the handle and doesn't suggest that any damage might have been done by the repeated retraction attempts.

 

I called Mooney and another recommended mechanic and they both thought that there was likely damage to the retraction mechanism -- at least a worn clutch and possibly some broken gears. Has anyone had a similar experience -- it seems that accidental unlatching of the manual handle is easy to do and I would imagine that a number of people have experienced this. At the very least, I need to add this to my checklist!

 

Thanks very much.

 

Warren Nagourney

Seattle, WA

[KSMooniac]

It does need to be added to the checklist.  I've not heard of damage caused by this event, but I don't know if doing it over and over could be bad.  If it were me, I would jack the plane up and use the manual extension system to lower the gear while listening for funny noises and feeling for unusual resistance.  Having another set of eyes watching the extension would be helpful too.

[markfoster7700]

I did this once very early on in the ownership of my Ovation 3.  I heard through some posts in the MAPA forum that I may have damaged a roll pin in the gear motor shaft or something to that effect.  But when I brought the subject up to Don Maxwell, he shrugged it off as a non-issue.  If he doesn't think it is a problem, I would tend to think that it is not a problem.  We did, however, put the plane up on jacks and swing the gear both manually and using the motor just to be sure that there were no bad noises or anything.  I have had the plane 6.5 years now, and never had an issue with the gear.

[warrennn]

Thanks for your responses. Yes, I find Don Maxwell's response reassuring. I would have thought that the service manual would have recommended a check of the actuator mechanism when this happens -- they only recommend relatching the manual lever and leaving it at that.

 

In 23 years, my only gear problems were a failure of a relay (which prevented the gear from retracting) and a failure of the airspeed switch (which could have been easily repaired, but the mechanic insisted on a new one for $800).

[Tommy]

23 years and only 3 posts?! Where have you been? 

[peevee]

Don't know if there's any truth to it, but the guy that checked me out in our plane said if that latch is undone the manual drive gear is engaged and strips out when you hit the electric drive.

[warrennn]

Yes, I have been a fairly avid consumer of this site, though I haven't contributed much (sorry). Actually, I have owned Mooneys for 30 years -- my former plane was a '68 M20C.

 

I might let the folks at Command Aviation in Bellingham look at it -- they have a good reputation and are the only authorized service center in WA. I spoke to the owner (?) and he wanted to take the entire actuator apart to make sure there are no broken off gear teeth floating around waiting to jam the gear in a partially extended position.  Sounds expensive.

[jlunseth]

I have not had this happen but Bruce Jaeger has told me about it for years. I should have done something about getting it on my checklist before now, and in light of my experience I am going to do it. Apparently a major cause is a back seat passenger who hits the latch with their foot.

[Andy95W]

Don't know if there's any truth to it, but the guy that checked me out in our plane said if that latch is undone the manual drive gear is engaged and strips out when you hit the electric drive.

Hopefully someone will correct me if I'm wrong, but I thought this was applicable only to the original electric gear from the '60s/70's, with the manual crank by the pilot's left knee.

[Bob - S50]

Yes, I have been a fairly avid consumer of this site, though I haven't contributed much (sorry). Actually, I have owned Mooneys for 30 years -- my former plane was a '68 M20C.

 

I might let the folks at Command Aviation in Bellingham look at it -- they have a good reputation and are the only authorized service center in WA. I spoke to the owner (?) and he wanted to take the entire actuator apart to make sure there are no broken off gear teeth floating around waiting to jam the gear in a partially extended position.  Sounds expensive.

 

As far as I know, the closest Mooney Service Center is at Troutdale (TTD) just east of Portland.  Advanced Aircraft (503-465-2298).  I've used them to change our clutch spring in the landing gear.  No sales tax either.

 

Bob

[carusoam]

Based on the OP's description...

(1) Something mechanically jammed the system enough to trip a circuit breaker several times.

(2) he clearly knows what jammed the system. (E gear extension was engaged)

(3) the original jam has been removed. (E gear extension was stowed)

(4) the level of damage to both systems is unknown until it can be inspected. (Suggestions were made)

(5) broken parts are expensive. Gear up landings are more expensive. (Make sure there is no damage)

(6) checking the E gear to be stowed has always been on my checklist.

Is there a Mooney maintenance procedure for inspection after this somewhat common mishap?

It is possible that the CB tripped preventing mechanical damage.

Let us know what you find....

Best regards,

-a-

[warrennn]

Tentatively, I will let the shop  I have used for the last 30 years do the initial inspection (Crown Aviation at Paine field, Everett WA). They are currently busy and won't be able to do anything for the next two weeks. The next closest shop is in Bellingham -- they might be the better choice if a more detailed inspection of the gear actuator is needed. I will keep the forum posted on the results.

 

Again, many thanks for the replies.

[warrennn]

My mechanic at my home field (Paine field, Everett, WA) finally jacked up the airplane and swung the gear repeatedly. He reported that there was absolutely no problem with it and it worked very well. I haven't flown it yet.

 

I guess that the breaker saved the mechanism. Of course, I will add the emergency gear check to my check list and be even more careful when I do a final "GUMP" before landing, in case anything was weakened by the experience.

[warrennn]

I flew the plane today for the first time since the incident and the gear worked fine. Unfortunately, I also noticed that the checklist -- a standard Mooney checklist for an M20K -- had an entry for checking the emergency gear system!!

 

I suppose that I have been ignoring this checklist item, perhaps thinking that it was not important. I need to be more scrupulous with checklists in the future!

[carusoam]

Congratulations on getting through the rough patch.

Thank you for the follow up.

Best regards,

-a-

[Randy_B]

I am late to this thread but, it is good to hear that no damage was done.  In the first 15 hours of ownership of my 84' M20J I found the evidence of this type of mishap.  I was still receiving my dual instruction and we practiced the emergency gear extension procedure by the book.  You could feel something was just not right.  When pulling the T-handle extension cable lightly and slowly the gear would extend.  If you pulled with more than light force it felt like the actuator skipped a gear or past a lobe.  My mechanic's investigation found the bronze clutch was damaged.  There were other things that suggested the gear override button was pressed while the gear extension lever was open.  IIRC I found the bronze clutch at LASAR for +/- $350.00.

[201LK]

I have had the same problem with a 1978 J Model.  No problems have been found in many annuals since.  Maybe I am lucky.  I think the problem occurs when a seatbelt catches the latch.  

[cnoe]

This issue was recently discussed in another thread titled "No back spring in landing gear actuators". Hyett6420 posted some outstanding pics of his actuator along with this one showing how the emergency extension clutch can be damaged.

As I understand it (which may or may not be correct) the emergency extension spindle (shown below) engages in this clutch recess and if it isn't tensioned correctly it can cause the damage shown. This could prevent one from being able to extend the gear manually.

As (possibly) designed and written about in the service literature the circuit breaker should trip if the emergency extension is engaged when the electric gear switch is activated. It sounds like yours did exactly that. I think that one would "hear" this sort of damage happening and that the gear would have come up at least partially as it stripped out.

As long as the emergency extension system still works fine and there was no perceived damage to your clutch you might be fine without tearing it all apart.

As many have said before... "I am not an A&P, just a PP".