No Back Clutch Spring M20-282-0001 Eaton Kit Update Good News

**PT20J** · October 26

25 minutes ago, donkaye said:

Before he retired, Tom Rouch from Top Gun, had the procedure down cold. I watched him do it. He could replace the back spring in a couple of hours--around $300. The back spring cost about $350 at the time.

He used to refurbish gear actuators. I bought one from him in 2016 to eliminate the Plessey actuator and its associated back spring issues (you couldn't get them). The price at the time was a little less than $5,000. New they were $15,000. The good old days just 8 years ago...

Don, good move to rid yourself of the Plessey. I believe all the failures resulting in gear ups (except for perhaps one due to a bad batch of springs years ago from Eaton) are in Plessey's and they've been out of production for years and no parts are available. Most recent was a M20J with a Plessey actuator that geared up June 12, 2022 (NTSB Accident Number ERA22LA319) that had a torsion spring break at the tang (Plessey called them torsion springs; Eaton called them no-back springs; Mooney seems to have generalized on the Eaton nomenclature). Interestingly, the torsion spring had been replaced 427 hours before the accident. (No idea where someone found the unobtainium part).

I would not be too concerned about an Eaton. Don Maxwell told me that the Eaton actuator is supposed to be designed for 20,000 operations. I don't know if that's correct or not, but it seems reasonable.

Tom also replaced the spring in my 1978 M20J many moons ago. I don't have any records for that airplane any longer, but I don't recall it being particularly expensive.

Skip

**EricJ** · October 26

15 minutes ago, PT20J said:

(Plessey called them torsion springs; Eaton called them no-back springs; Mooney seems to have generalized on the Eaton nomenclature).

The nomenclature does seem to be fairly unique to this application. I think usually they're just called a "backstopping clutch".

These guys apparently specialize in spring clutches:

https://www.tinyclutch.com/spring-clutches.htm

Interestingly, AS has a generic "spring clutch" that is FAA-PMA for $274, but no idea what it's for. Looks like no tangs, too.

https://www.tinyclutch.com/spring-clutches.htm

**PT20J** · October 26

I believe that the no-back spring is technically a wrap spring brake/clutch.

Here's a video that explains the idea. Note, however that the Mooney actuator design is different because it has no friction disks and only needs to brake in the gear down direction to prevent the wheels from descending since there are no up locks. It doesn't back drive when the wheels are down due to the overcenter locking of the gear components.

**toto** · October 26

1 hour ago, bluehighwayflyer said:

A STC’d Johnson bar using as many factory parts as possible for the entire M20 product line sure would be nice. It might be back to the stone ages but at least it would guarantee airworthiness and avoid situations such as this moving forward in at least one of our complex but critical systems.

It might require lower gear speeds for later models, but that is generally just a descent planning issue.

I seriously want someone who really understands this stuff to figure out where to put a zip tie so the manual extension cable still works after the spring breaks.

Gear actuators aren’t infallible, but most RG planes have an emergency extension system that doesn’t have a single point of failure with the primary. If someone can noodle an STC that eliminates the single point of failure, we’ll stop stressing about the spring.

**PT20J** · October 26

31 minutes ago, toto said:

I seriously want someone who really understands this stuff to figure out where to put a zip tie so the manual extension cable still works after the spring breaks.

Gear actuators aren’t infallible, but most RG planes have an emergency extension system that doesn’t have a single point of failure with the primary. If someone can noodle an STC that eliminates the single point of failure, we’ll stop stressing about the spring.

The emergency gear extension system only protects against electrical failures. If the spring breaks, it jams up the gear train and the emergency system won’t work either, no matter where you put a zip tie.

There are gear ups almost weekly caused by pilots failing to put the gear down. Happens with the manual gear, too. By comparison, there have only been a handful of spring failures over decades. Some of us are stressing out over a very small risk.

**toto** · October 26

1 minute ago, PT20J said:

The emergency gear extension system only protects against electrical failures. If the spring breaks, it jams up the gear train and the emergency system won’t work either, no matter where you put a zip tie.

There are gear ups almost weekly caused by pilots failing to put the gear down. Happens with the manual gear, too. By comparison, there have only been a handful of spring failures over decades. Some of us are stressing out over a very small risk.

The “zip tie” comment was meant to be tongue in cheek, but it does seem like an unfortunate design for an emergency extension system.

I’m mostly eating popcorn in this thread - totally agree that NBS failures aren’t the reason people land Mooneys gear-up, and gear-up landings rarely hurt more than the pilot’s pride, in any case..

**EricJ** · October 27

3 hours ago, toto said:

Gear actuators aren’t infallible, but most RG planes have an emergency extension system that doesn’t have a single point of failure with the primary. If someone can noodle an STC that eliminates the single point of failure, we’ll stop stressing about the spring.

Mooney's aren't necessarily unique this way. Cessna singles are electro-hydraulic with hydraulic hand pump backup. That means if the fault is hydraulic-related, e.g., a leak or depletion of the fluid, you won't be able to pump it down. Some Pipers, e.g., Arrows, Seminoles, rely on gravity to drop the gear if there's an issue, which doesn't always work. It's not uncommon to see Cessnas or Pipers with one gear leg unable to extend, and there's no way to get it down. I think we've all seen vids of airplanes landing gear-up, and there's a videographer there to catch it because they're landing that way because the emergency gear extension didn't work.

That doesn't make us feel any better, I'm sure, but we're definitely not alone this way.

**Will.iam** · October 28

And doesn’t the spring most likely fail when the gear is down and you try to bring it up? Thus it’s still down and you can still land? Reminds me of garage door springs that the maximum tension is when the door is down thus when the spring breaks the door is already down. I would hate to see the unfortunate soul or car that is under a garage door that happens to be open and have a spring fail as that door would go crashing down and cause some severe damage. But again when the door is open is when the spring is most relaxed and not as likely to break.

**toto** · October 28

1 hour ago, Will.iam said:

And doesn’t the spring most likely fail when the gear is down and you try to bring it up? Thus it’s still down and you can still land? Reminds me of garage door springs that the maximum tension is when the door is down thus when the spring breaks the door is already down. I would hate to see the unfortunate soul or car that is under a garage door and have a spring fail as that door would go crashing down and cause some severe damage.

Yes, they seem to fail more often on retraction than extension

1980Mooney · October 28

3 hours ago, Will.iam said:

And doesn’t the spring most likely fail when the gear is down and you try to bring it up? Thus it’s still down and you can still land? Reminds me of garage door springs that the maximum tension is when the door is down thus when the spring breaks the door is already down. I would hate to see the unfortunate soul or car that is under a garage door that happens to be open and have a spring fail as that door would go crashing down and cause some severe damage. But again when the door is open is when the spring is most relaxed and not as likely to break.

I don't know if it happens more on retraction or during extension but you have the danger backwards. Per Tom Rouch, who used to run Top Gun Aviation Mooney Service Center before he retired:

"If the no-back clutch spring breaks while retracting the gear, the gear will not go down for landing. If it breaks during extension, the gear will go down, and probably hold the gear down. You probably won't know that the no-back clutch spring is broken until the next flight when the gear won't retract. The main defect in this gear system is that the emergency extension depends on an intact no-back clutch spring. "
See Mooney Flyer August 2017, page 17-19
- https://themooneyflyer.com/issues/2017-AugTMF.pdf

Edited October 28 by 1980Mooney
Noted that I have no idea if it happens more on retraction or during extension.

**toto** · October 28

6 minutes ago, 1980Mooney said:

You have it backwards. Per Tom Rouch, who used to run Top Gun Aviation Mooney Service Center before he retired:

If the no-back clutch spring breaks while retracting the gear, the gear will not go down for landing.
If it breaks during extension, the gear will go down, and probably hold the gear down. You probably
won't know that the no-back clutch spring is broken until the next flight when the gear won't
retract. The main defect in this gear system is that the emergency extension depends on an intact
no-back clutch spring.

See Mooney Flyer August 2017, page 17-19

https://themooneyflyer.com/issues/2017-AugTMF.pdf

My understanding has been that you’re more likely to break a spring on retraction than extension, and that it’s likely to happen early - so the gear are still locked down with a broken spring.

But I have no data to back this up (there are so few incidents that I doubt there’s good data in any case) .. and I’m certainly not going to argue anecdotes with Tom Rouch.

1980Mooney · October 28

2 hours ago, Will.iam said:

And doesn’t the spring most likely fail when the gear is down and you try to bring it up?

1 hour ago, toto said:

Yes, they seem to fail more often on retraction than extension

There are four (4) cases of NBS No-back Spring failure in the FAA ASIAS database.

M20J Sept. 15, 1991
M20R July 5, 2003
M20S Oct. 30, 2002
M20J May 15, 2005

The problem is that it does not distinguish Plessey actuator failures from Eaton actuator failures. The Eaton actuator NBS is the subject of this topic. As you all know the Plessey actuator is on longer supported. Tom Rouch, in the same Mooney Flyer article said:

"I have dealt with planes that have a broken no-back clutch spring. Most of these had Plessey actuators, which were used in the late 90s. These use a slightly different spring from all other actuators. The Plesseys are now obsolete and their no-back clutch springs are not available."
https://themooneyflyer.com/issues/2017-AugTMF.pdf p. 17-19

FAA ASIAS NBS Failures

**cliffy** · October 28

Some owners are required to comply with every SB published by regulation.

If yours breaks and you don't wreck your airplane on landing how much is a spring worth to you now if your airplane is now just a big paper weight without it? Part it out?

Have any of you priced parts new from Cessna or Beech lately?

Parts are not priced on production costs but are valued in relation to what the new airplane costs NOW not 40 or 50 years ago.

What does a new 4 place airplane cost today? $900,000?

As an example - just the minerals that have to be mined that go into making wind generators have gone up @90 percent in the last year or so.

I find it interesting that here on this forum we talk constantly of spending $25,000 to $50,000 dollars to flush our panel and install the newest and fanciest avionics with nary a complaint on the price and yet $3K for a landing gear part seems to raise the hackles on many. And yet in many instances the same equipment meant for the experimental market is priced at 20% of the certified stuff with no similar complaint on pricing,

The price is what the price is. You buy it or you don't. Its a cost of entry to the world of aviation. CB need not apply. This flying game isn't for the faint of heart.

Many owners waste 3 times that much on buying a new airplane acquisition in their first annual because they didn't heed the warning about a proper pre-buy.

Seems to me the cost of this part is minor if the airplane is a boat anchor without it.

$3000 vs. $80,000 Hmmmmm.

**Pinecone** · October 28

If I need a spring, $3K is reasonable.

But it is too much to buy one just in case. $1500? I would probably buy one to have one on the shelf.

Slick Nick · October 28

1 hour ago, Pinecone said:

If I need a spring, $3K is reasonable.

But it is too much to buy one just in case. $1500? I would probably buy one to have one on the shelf.

But do you buy it to have a spare on the shelf? Or do you have it installed and keep your original as a spare?

What is the failure mode of this spring? Is this design any better / more durable? Is there something about the new spring that precludes the likelihood of failure compared to my stock one? Or is it the exact same design, and it should be more durable simply by the fact that it's got fewer cycles on it?

**cliffy** · October 28

The failure mode of the spring was one of the "ears" breaking off due to minute cracks in the bend area in a production run of springs. It had something to do with the heat treatment.

The new springs SEEM to be exact clones of the historical design. Once the failure mode was determined subsequent production runs didn't seem to have any failures IIRC.

Historically, as noted, very few springs failed but if it does you have a real problem in flight.

**PT20J** · October 28

12 hours ago, 1980Mooney said:

There are four (4) cases of NBS No-back Spring failure in the FAA ASIAS database.

M20J Sept. 15, 1991

M20R July 5, 2003

M20S Oct. 30, 2002

M20J May 15, 2005

The problem is that it does not distinguish Plessey actuator failures from Eaton actuator failures. The Eaton actuator NBS is the subject of this topic. As you all know the Plessey actuator is on longer supported. Tom Rouch, in the same Mooney Flyer article said:

"I have dealt with planes that have a broken no-back clutch spring. Most of these had Plessey actuators, which were used in the late 90s. These use a slightly different spring from all other actuators. The Plesseys are now obsolete and their no-back clutch springs are not available."

https://themooneyflyer.com/issues/2017-AugTMF.pdf p. 17-19

FAA ASIAS NBS Failures

https://www.asias.faa.gov/apex/f?p=100:18:::NO::AP_BRIEF_RPT_VAR:19910915046159I

https://www.asias.faa.gov/apex/f?p=100:18:::NO::AP_BRIEF_RPT_VAR:20030705013639I

https://www.asias.faa.gov/apex/f?p=100:18:::NO::AP_BRIEF_RPT_VAR:20031030030799I

https://www.asias.faa.gov/apex/f?p=100:18:::NO::AP_BRIEF_RPT_VAR:20050515016429I

The last one is a mystery. Someone isn't telling the truth. But the investigator (whoever that was) could not find anything wrong with the actuator.

The second and third reports involved a M20R and M20S, respectively. Those likely had Plessey actuators.

1980Mooney · October 28

10 hours ago, cliffy said:

Some owners are required to comply with every SB published by regulation. If yours breaks and you don't wreck your airplane on landing how much is a spring worth to you now if your airplane is now just a big paper weight without it? Part it out?

Parts are not priced on production costs but are valued in relation to what the new airplane costs NOW not 40 or 50 years ago. What does a new 4 place airplane cost today? $900,000?

I find it interesting that here on this forum we talk constantly of spending $25,000 to $50,000 dollars to flush our panel and install the newest and fanciest avionics with nary a complaint on the price and yet $3K for a landing gear part seems to raise the hackles on many. And yet in many instances the same equipment meant for the experimental market is priced at 20% of the certified stuff with no similar complaint on pricing,

Seems to me the cost of this part is minor if the airplane is a boat anchor without it.

$3000 vs. $80,000 Hmmmmm.

You just made the case for Lasar to raise the price even more. Heck it would still be a bargain at $6,000 or even $12,000 for the spring given the price to repair or replace the geared up Mooney.

But that logic and reality is exactly what is driving Private Equity to buy up general aviation suppliers. and raise prices. Hartzell/Arcline Investment acquisition and price increase has been discussed here. Vance Street Capital Partners bought McFarlane, Tempest, Marvel-Schebler, AirForms, PMA Parts, Precision Airmotive, Alcor, CFS Fuel Systems, etc and call is VS Victor Sierra Aviation Holdings. Lesser know is Warburg Pincus's early move to acquire and consolidate aviation avionics suppliers primarily to the Department of Defense - it is called Extant Aerospace and now owned by TransDigm. They bought the old Goodrich/L3 Harris line for instance. They are not shy about jacking prices and screwing everyone including the DOD. If you have a WX-500 for instance, they are now selling it for $23,000.

Edited October 28 by 1980Mooney

**MikeOH** · October 28

@1980Mooney

Spot on!

Also, as to the 'spending $25K to $50K' on a new panel...how does that even rise to an apples to oranges comparison?? You get an awful lot of sophisticated electronics, capability, an the installation for that money. To compare that value to a single piece of heat treated spiral metal the size of quarter for $3,000 is absurd!

1980Mooney · October 28

24 minutes ago, MikeOH said:

@1980Mooney

Spot on!

Wanna guess one of the companies Transdigm owns? Eaton! You know, the guys making this spring. $3,000 each a coincidence? I think not.

Uhhh.....you might want to check your sources.

**MikeOH** · October 28

28 minutes ago, 1980Mooney said:

Uhhh.....you might want to check your sources.

Crap! Thanks for checking! Correcting my post.

I got my unobtanium/overpriced parts sources mixed up; Transdigm owns what's left of Dukes...the worm gear issue.

**PT20J** · October 28

All the price increase may not be solely due to LASAR's markup or EATON price. If you were the CEO of Mooney and were strapped for cash and held the keys to the kingdom, would you turn the keys over to someone for free? I wouldn't. For all we know, it's a three way split: $1000 for EATON, $1000 for Mooney, $1000 for LASAR. We don't know. And frankly, it's none of our business. Privately held companies do not generally share a lot details of their cost structure with their customers. But, if you need/want a spring, this is the only game in town.

**MikeOH** · October 28

@PT20J

Only disagree with your last sentence. If I was in need of this spring I would go OPP way before getting ripped off for $3K. I'm retired and my time is free; plus, as I get older, it is much harder to bend over

**PT20J** · October 28

3 minutes ago, MikeOH said:

@PT20J

Only disagree with your last sentence. If I was in need of this spring I would go OPP way before getting ripped off for $3K. I'm retired and my time is free; plus, as I get older, it is much harder to bend over

I would be truly amazed if you could get a OPP for $3K.

**MikeOH** · October 28

15 minutes ago, PT20J said:

I would be truly amazed if you could get a OPP for $3K.

Perhaps. But the few minutes I spent on-line showed a plethora of torsional spring manufacturers with plenty of custom capabilities touted. Unlike hobbing tight tolerance worm gear pairs, these appear to be a simple wind of the appropriate material around a mandrel, followed by heat treat. Just doesn't look like the kind of part requiring much, if any, custom tooling. A set-up fee and minimum buy, certainly. Let's just say I'd spend a fair amount of time looking into it before getting hosed by LASER/EATON/MOONEY/ET AL.

Yes, we fly what would be $900K airplanes new that many of us would never be able to afford to buy, yet we mange to maintain them. While I'm an avowed CB I'll spend what it takes to keep my plane safe; I spent over $600 last year on the intake duct. I thought that was pushing it, but trying to OPP that thing would be a nightmare! But I have to draw the line somewhere...and $3,000 for this stupid spring is WAY past that line. YMMV, of course.

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