Real Risk of Gear Box Failure

[Matthew P]

2 hours ago, warbingtonmasonry said:

Good afternoon.

I have read here over the years several threads re: electric gear wear and ADs and malfunction worries.

Because of those worries, I have recently completed the removal of field-installed electric gear and installation of manual gear retraction system.

I have not yet checked the retraction system rigging. I don't really want to spend $350 for two rigging tools.

The tools appear to me to provide a secure way to fasten a torque wrench to the retraction truss at a certain point in space for which the overcenter break torque is specified.

My 1967 M20F left the factory with manual gear retraction system.

I plan to offer my complete electric retraction system, as removed, for sale soon.

When you do, please let me know, is it a dukes or itt actuator?

[Matthew P]

3 hours ago, warbingtonmasonry said:

Good afternoon.

I have read here over the years several threads re: electric gear wear and ADs and malfunction worries.

Because of those worries, I have recently completed the removal of field-installed electric gear and installation of manual gear retraction system.

I have not yet checked the retraction system rigging. I don't really want to spend $350 for two rigging tools.

The tools appear to me to provide a secure way to fasten a torque wrench to the retraction truss at a certain point in space for which the overcenter break torque is specified.

My 1967 M20F left the factory with manual gear retraction system.

I plan to offer my complete electric retraction system, as removed, for sale soon.

You can pay $350 now or thousands later..you will need them for your annuals here on out, alternative may be asking the shop that does your current annual to borrow them

[Nico1]

If anyone's interested in selling their LG rigging tool (for main gear) let me know

[47U]

9 minutes ago, Nico1 said:

If anyone's interested in selling their LG rigging tool (for main gear) let me know

I think there’s a pretty good chance LASAR has it in stock…

https://lasar.com/tools/main-gear-rigging-tool-gse030007-100?rq=Rigging

[N201MKTurbo]

https://www.knr-inc.com/products-list.html?view=article&id=133:knr-tools-mooney-landing-gear&catid=87:tools

https://lasar.com/gear-tools

 

[N201MKTurbo]

Having one of these helps:

https://www.grainger.com/product/PROTO-Dial-Torque-Wrench-3-8-in-1ARP9?opr=PLADS&analytics=FM%3APLA&a2c_sku_original=1ARP7&position=3

[1980Mooney]

On 6/17/2024 at 1:13 PM, warbingtonmasonry said:

Good afternoon.

I have read here over the years several threads re: electric gear wear and ADs and malfunction worries.

Because of those worries, I have recently completed the removal of field-installed electric gear and installation of manual gear retraction system.

I have not yet checked the retraction system rigging. I don't really want to spend $350 for two rigging tools.

The tools appear to me to provide a secure way to fasten a torque wrench to the retraction truss at a certain point in space for which the overcenter break torque is specified.

My 1967 M20F left the factory with manual gear retraction system.

I plan to offer my complete electric retraction system, as removed, for sale soon.

It seems like an extreme solution to something that does not currently exhibit any problems (you don't mention whether it is a Dukes or Eaton).  It's kind of like removing a functioning vintage auto-pilot from your plane and hand flying because you fear it might malfunction one day.  

Granted that you save some weight, but it is no silver bullet solution.  There are a lot of J-bar gear ups/gear collapses. - probably more than you think.

Most of these early 2024 reported incidents below are gear-ups/gear collapse.  You have to dig into each one to see - and on some of the E, F's you have to search to see if there is history of electric gear being installed.  I think about 5-6 incidents during Feb-March are J-bar gear-ups/gear collapse.  You can't always identify the cause (pilot vs. mechanical).

https://www.asias.faa.gov/apex/f?p=100:12:::NO:12::

 

Edited June 24, 2024 by 1980Mooney

[PT20J]

I used to instruct at a club that had a M20C with manual gear. Over a period of about fifteen years, it landed gear up three times.

[Shadrach]

4 minutes ago, PT20J said:

I used to instruct at a club that had a M20C with manual gear. Over a period of about fifteen years, it landed gear up three times.

How many were mechanical failures?

[PT20J]

1 hour ago, Shadrach said:

How many were mechanical failures?

 None. Which is really the point. The number of gear up landings caused by mechanical failures (J-bar or electric) is very small compared to pilot errors. Just like driving, the nut behind the wheel is the most likely component to fail. I don't worry about the gear failing to come down (although since I had a relay and then a microswitch fail, I have some concern about it going up); but I do very much worry about getting distracted by unusual ATC requests, traffic or some unrelated emergency. 

[Shadrach]

2 hours ago, PT20J said:

 None. Which is really the point. The number of gear up landings caused by mechanical failures (J-bar or electric) is very small compared to pilot errors. Just like driving, the nut behind the wheel is the most likely component to fail. I don't worry about the gear failing to come down (although since I had a relay and then a microswitch fail, I have some concern about it going up); but I do very much worry about getting distracted by unusual ATC requests, traffic or some unrelated emergency. 

Agree that it is most often human failure. However, it does seem that there have been a number of threads centering on electric gear issues lately. 

[PT20J]

1 hour ago, Shadrach said:

Agree that it is most often human failure. However, it does seem that there have been a number of threads centering on electric gear issues lately. 

The electric system is more complicated, so I would expect it to have more issues. But, mechanically, it is very similar and the emergency gear extension system will protect you from electrical failures. If everyone had upgraded to the 40:1 gears in the Dukes and lubricated them properly, the actuators would probably outlast the airframe. Similarly, the Eaton noback springs are really a non-issue as far as I can tell. So, that leaves the Plessey actuators. There have been several documented failures. It is known only to Mooney how many of these actuators were installed, but my guess is not many which would make the failure rate higher, and you cannot get parts for them. Some will say you cannot get parts for Dukes or Eatons either, but at least Eaton is still in business making it a possibility.

[cliffy]

Many months ago I asked for a letter of no technical objection from Mooney about using the spring actuator rods

on the J bar landing gear and was told they would talk it over. Nothing has come of it yet. 

If they could be used (which I feel is a real possibility) then much of the monkey motion of rigging the J bar gear 

would be eliminated. 

I can see no reason why it wouldn't work. Yu get the proper over center torque either way. 

Anyone who "adjusts" the gear on a Mooney without reference to the correct tools is playing with fire. 

And, you can't just drop in on the complete rigging directions in any place you want. 

You have to start at the beginning a follow the entire procedure through.