No Back Spring Update

[A64Pilot]

I ordered an NBS back in May and was told it would be a few months as they come in batches, well the expected date slipped once or twice, last date was Dec, so I decided to call and ask if they had an update, below is the answer. I left out the signature block as I didn’t know if it was proper to include it, but it’s a well respected MSC so I assume what they said is real.

“Joseph,

 

So I’ve heard back from the factory and they are having quality control issues with the new springs they’ve received from Eaton.  Until Eaton resolves their manufacturing issues the factory will not be ordering more and cannot sell the messed up ones they have.  The factory is working with Eaton to try to get this resolved.

Regards,”

[Larry]

I heard that Eaton had a heat treating issue causing the springs to not have the correct tension.  I believe the problem was discovered by Joey Cole.  

[jetdriven]

The whole cause for this no back spring debacle is improper manufacturing. A clock spring by definition has an infinite service life.

[ilovecornfields]

Does this apply to the spring they sold me last year?

[jetdriven]

they never admitted the 1994 batch was defective, which caused the SB which said replace every 2000hr, and which some of those are also defective.

[1980Mooney]

4 hours ago, jetdriven said:

The whole cause for this no back spring debacle is improper manufacturing. A clock spring by definition has an infinite service life.

 

1 hour ago, jetdriven said:

they never admitted the 1994 batch was defective, which caused the SB which said replace every 2000hr, and which some of those are also defective.

 

1 hour ago, bluehighwayflyer said:

I agree.  I can’t help suspecting that a single bad batch, most of which are out of service by now, is responsible for most if not all of this. Especially in the absence of new parts being available, it wouldn’t be bad PM to just clean and lubricate the actuator every 1000 hours, per the SB, and leave existing and proven NBC springs in service.  

"leave existing and proven NBC springs in service.  "

Exactly.  What this means is that if your NB spring has not failed by now in the past 20+ years since Service Bulletin SBM20-279C was issued (Revised September 11, 2002) then it is not going to fail. 

And now we learn that owners which had actuators with perfectly good NB springs, at the cautionary recommendation of the SB, installed (at great expense) potentially defectively manufactured new NB springs from Eaton/Mooney.   Apparently through all this Eaton (or its predecessors Eaton/Vickers and Avionic Products) was unable to trace the original 1994 manufacturing defects and is unable to trace and identify (or even recognize defects until others point it out) manufacturing defects in new NB springs that it has been shipping for who knows how long (years?).  So now there is a new bad batch of NB springs that have been introduced into the fleet and in service.

So that means that @ilovecornfields, or other owners that recently replaced NB springs, may need to "again" replace, as a precaution, the "new" NB spring that he replaced last year as a precaution to begin with......

What a cluster.  What a waste of time and money.  

I have no intention of replacing my NB spring as long as I continue to own this Mooney.

Edited February 2, 2023 by 1980Mooney

[StevenL757]

On 1/31/2023 at 8:20 AM, A64Pilot said:

I ordered an NBS back in May and was told it would be a few months as they come in batches, well the expected date slipped once or twice, last date was Dec, so I decided to call and ask if they had an update, below is the answer. I left out the signature block as I didn’t know if it was proper to include it, but it’s a well respected MSC so I assume what they said is real.

“Joseph,

So I’ve heard back from the factory and they are having quality control issues with the new springs they’ve received from Eaton.  Until Eaton resolves their manufacturing issues the factory will not be ordering more and cannot sell the messed up ones they have.  The factory is working with Eaton to try to get this resolved.

Regards,”

Exactly right…the quality control issue is accurate; whereas, the defective springs will simply not install correctly inside the actuator; hence, not rotate as they should per the install instructions.  The defect is obvious when you try to fit the spring.

I’ve been waiting on a spring kit for well over a year, and if the shop you mention above is who I think it is, that shop currently has (or did have) quite a few spring kits in stock, but were refusing to sell to anyone who wasn’t a customer of theirs, and/or wouldn’t agree to have the kit installed at their shop.  Not sure if any of the kits in their possession were defective or not, but I never got an opportunity to find out, so it puts me right back to waiting like many other folks.  Frustrating to say the very least.

1 hour ago, ilovecornfields said:

Does this apply to the spring they sold me last year?

Most likely not, if that kit you purchased was installed successfully.

[StevenL757]

1 hour ago, jetdriven said:

they never admitted the 1994 batch was defective, which caused the SB which said replace every 2000hr, and which some of those are also defective.

Hey Byron…My understanding - based on a couple of reputable IAs who attempted to replace some springs of-late discovered what I wrote above; which was the defective springs simply couldn’t be fully-installed in the actuators and the installs aborted.  Were you aware of a different defect stemming from a bad batch, circa-1994?  Just making sure I’m tracking 100% on this.

[Rick Junkin]

7 minutes ago, StevenL757 said:

and if the shop you mention above is who I think it is

I’m weary of posts not naming names. Steve Leary, who is the shop of which you are speaking?!!!

[ilovecornfields]

55 minutes ago, 1980Mooney said:

So that means that @ilovecornfields, or other owners that recently replaced NB springs, may need to "again" replace, as a precaution, the "new" NB spring that he replaced last year as a precaution to begin with......

What a cluster.  What a waste of time and money.  

I have no intention of replacing my NB spring as long as I continue to own this Mooney.

Mine is still sitting in a bag in the hangar. I never said I replaced it.

[1980Mooney]

53 minutes ago, StevenL757 said:

Hey Byron…My understanding - based on a couple of reputable IAs who attempted to replace some springs of-late discovered what I wrote above; which was the defective springs simply couldn’t be fully-installed in the actuators and the installs aborted.  Were you aware of a different defect stemming from a bad batch, circa-1994?  Just making sure I’m tracking 100% on this.

Mooney owners have been chasing their tail on this for 25 years.  Back in 2013 on MS it was reported that a single failure in the late 90's led to the SB SBM20-282.  Additionally on page 8 of the Service Bulletin (attached) Eaton states that they believe the failure was an isolated incident.  And in 2003, the first Eagle M20S Serial number 30-0001 N2234X suffered a No-Back spring failure at 178 hours since compliance with the SB with a "new" No-Back spring.  They are all probably Eaton manufacturing (heat treat or material ) quality defects leading to weak "tangs" on the springs that break off.

FAA Incident Report: "IN FLIGHT, 178.3 HOURS SINCE COMPLIANCE WITH MFG SB AND MANDATORY REPLACEMENT OF NO BACK CLUTCH SPRING WITH NEW. BOTH TANG ENDS BROKE OFF OF SPRING INSIDE OF LANDING GEAR ACTUATOR WHEN GEAR WAS SELECTED DOWN FOR LANDING. ONE BROKEN TANG APPARENTLY JAMMED BETWEEN THE NO BACK CLUTCH SPRING AND THE NO BACK CLUTCH SPRING HOUSING MAKING EITHER ELECTRICAL OR EMERGENCY MANUAL EXTENSION OF THE LANDING GEAR IMPOSSIBLE. AC WAS LANDED, GEAR UP, UNEVENTFULLY BUT SUBSTANTIAL DAMAGE TOPROPELLER AND BOTTOM OF FUSELAGE WAS CAUSED BY CONTACT WITH RUNWAY. INVESTIGATION UNDER WAY, OTHER REPORTS OF IDENTICAL FAILURES."

SBM20-282-A No Back Spring.pdf

 

 

Edited February 2, 2023 by 1980Mooney

[Pinecone]

Wasn't there someone here on MS that was going to make NBS under their PMA?

I seem to recall they were looking for a new one to measure and a broken one to do materials analysis to figure out the proper alloy.

[StevenL757]

9 hours ago, Rick Junkin said:

I’m weary of posts not naming names. Steve Leary, who is the shop of which you are speaking?!!!

Maxwell

[StevenL757]

8 hours ago, 1980Mooney said:

Mooney owners have been chasing their tail on this for 25 years.  Back in 2013 on MS it was reported that a single failure in the late 90's led to the SB SBM20-282.  Additionally on page 8 of the Service Bulletin (attached) Eaton states that they believe the failure was an isolated incident.  And in 2003, the first Eagle M20S Serial number 30-0001 N2234X suffered a No-Back spring failure at 178 hours since compliance with the SB with a "new" No-Back spring.  They are all probably Eaton manufacturing (heat treat or material ) quality defects leading to weak "tangs" on the springs that break off.

Ok, thanks for reviving that content.  It sounds like the latest batch of springs released is exhibiting a different type of failure.

[1980Mooney]

2 hours ago, Pinecone said:

Wasn't there someone here on MS that was going to make NBS under their PMA?

I seem to recall they were looking for a new one to measure and a broken one to do materials analysis to figure out the proper alloy.

Yes - easy to say but the challenges that Eaton faces telegraphs that this is not as simple as it sounds.  Like much of Mooney there is art to the science - much of which is being lost over time.  Some of that knowledge was learned through trial and error - so let's not forget the potential liabilities for a new "supplier".  How will it be tested over time?  And if a tang fails jamming the gear mechanism leading to a gear-up I would expect everyone to sue the crap out of that supplier.....Unlikely anyone will show up to try this.

[GeeBee]

My understanding is McFarlane was expressing interest. 

Making this spring is not rocket science.

[mooniac15u]

1 hour ago, GeeBee said:

Making this spring is not rocket science.

What if you install it in a Mooney Rocket?

[1980Mooney]

@StevenL757  Here is the latest No-back Spring "tang" failure documented by NTSB investigation. - November 2022

Report_ERA22LA319_105499_2_2_2023 11_04_56 PM.pdf

Analysis

After arrival to the destination airport near the conclusion of a cross-country flight the private pilot reported the landing gear circuit breaker (CB) tripped after he attempted to lower the landing gear electrically via the normal method. He reset the CB and again attempted to lower the landing gear via the normal method, but the same CB tripped. He overflew the airport then flew towards the coast where he reviewed the airplane’s Pilot’s Operating Handbook and attempted multiple times to manually lower the landing gear but was unsuccessful. He also contacted his mechanic to obtain assistance, but he was unable to lower the landing gear. At the suggestion of his mechanic, he diverted to a larger nearby airport where he performed a go-around on the first approach because the flight was too fast, then returned and landed gear-up.

According to maintenance personnel associated with recovery of the airplane, lowering the landing gear required them to disconnect the push/pull tubes near the landing gear actuator for each landing gear. Further, the emergency cable activation lever would not move and was “jammed….” Following removal of the push/pull tubes near the actuator the emergency cable activation lever would only travel about 90%. Following removal of the actuator from the airplane, manual operation revealed the actuator turned freely in the retracted direction but would not turn in the gear extension direction. Disassembly inspection of the clutch drive assembly of the landing gear actuator revealed one “tang” of the torsion spring associated with gear extension was fractured. By system design the emergency extension system did not bypass the clutch and damaged spring; thus, a single point failure (torsion spring) precluded manual and normal extension of the landing gear. According to airframe manufacturer, the landing gear actuator and fractured torsion spring are no longer available or supported, but they do have a retrofit for the landing gear actuator.

An airframe manufacturer service instruction specified replacement of the torsion spring in the drive clutch assembly of the landing gear actuator was last performed nearly 5 years and 427 hours earlier. The service instruction, due every 1,000 hours, was due again in about 573 Page 2 of 5 ERA22LA319 hours. The mechanic who performed the airplane’s last annual inspection nearly 8 months and 49 hours earlier reported that as part of that inspection he performed in part, normal and emergency extension checks of the landing gear and found no issues. He did not perform any maintenance to the landing gear except for lubrication.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be: The failure of the torsion spring inside the drive clutch assembly of the landing gear actuator which prevented normal and manual extension of the landing gear.

Findings

Aircraft - Landing gear actuator - Failure

Personnel issues - Use of equip/system - Pilot

[toto]

11 minutes ago, 1980Mooney said:

According to airframe manufacturer, the landing gear actuator and fractured torsion spring are no longer available or supported, but they do have a retrofit for the landing gear actuator.

The "retrofit" is a replacement actuator?  I've heard of zero pilots on MooneySpace doing this - is there actually an available aftermarket actuator that does not have a NBS?

[PT20J]

23 hours ago, 1980Mooney said:

FAA Incident Report: "IN FLIGHT, 178.3 HOURS SINCE COMPLIANCE WITH MFG SB AND MANDATORY REPLACEMENT OF NO BACK CLUTCH SPRING WITH NEW. BOTH TANG ENDS BROKE OFF OF SPRING INSIDE OF LANDING GEAR ACTUATOR WHEN GEAR WAS SELECTED DOWN FOR LANDING. ONE BROKEN TANG APPARENTLY JAMMED BETWEEN THE NO BACK CLUTCH SPRING AND THE NO BACK CLUTCH SPRING HOUSING MAKING EITHER ELECTRICAL OR EMERGENCY MANUAL EXTENSION OF THE LANDING GEAR IMPOSSIBLE. AC WAS LANDED, GEAR UP, UNEVENTFULLY BUT SUBSTANTIAL DAMAGE TOPROPELLER AND BOTTOM OF FUSELAGE WAS CAUSED BY CONTACT WITH RUNWAY. INVESTIGATION UNDER WAY, OTHER REPORTS OF IDENTICAL FAILURES."

 

Do you know if that incident involved a Plessey or an Eaton actuator?  I know that Mooney was using both well into the 1990s and the accident reported by @1980Mooney(NTSB Accident Number ERA22LA319) involved a Plessey actuator with only 427 hours since spring replacement. Plessey and Eaton are similar but different designs. Plessey calls the spring a torsion spring and Eaton calls it a no-back spring. Mooney has taken to just referring to both as no-back springs. They may or may not be identical parts -- probably not.

The original service instruction M20-52 from 1/15/92 listed 2 failures of springs in Plessey actuators at 1200 and 1500 hours respectively. It included GEC/Plessey service instruction SI-11 requiring replacing the spring every 1000 hours. This appears to be the origin of the 1000 Hour replacement interval. I found two additional SDR reports of failures of Plessey actuators (one a broken spring and the other of undetermined cause, but likely the spring from the description). With the accident cited above, that makes at least 4, maybe 5, Plessey spring failures.

Service bulletin M20-266A cites a single failure of an Eaton spring and lists a limited number of aircraft that require removal of the Eaton actuator and it's return to Eaton. This is likely the source of the idea that it was a problem related to a particular lot of springs.

Subsequently, Eaton issued service instruction SI102000-901-1 that called for inspection of ALL actuators within 100 hrs and recommended replacement of the spring at 1000 hour intervals. Mooney published this as service bulletin M20-279. Apparently, all these bulletins and instructions were causing confusion so Mooney issued a comprehensive consolidated version as M20-282A. 

So, after all the dust settles, as of 9/22/2004 (the issue date of M20-282A), Mooney has only noted the failure of ONE Eaton actuator spring, which may have been limited to one lot of actuators, whereas 4 or 5 Plessey actuators are known to have suffered spring failures.

So, I would be concerned if I had a Plessey actuator because of the several documented failures, but I'm not so sure that the Eaton's are much of a problem. It would be nice if Mooney would publish the actual number of failures of each type.

Skip

 

[1980Mooney]

24 minutes ago, toto said:

The "retrofit" is a replacement actuator?  I've heard of zero pilots on MooneySpace doing this - is there actually an available aftermarket actuator that does not have a NBS?

NO.  That plane is a 1992 M20J - Ser. 24-3261 - 24 volt actuator.  Eaton made 3 different 24 volt actuators: 

560254 - 503, -505 and -507

 

 

Edited February 3, 2023 by 1980Mooney

[PT20J]

14 minutes ago, toto said:

The "retrofit" is a replacement actuator?  I've heard of zero pilots on MooneySpace doing this - is there actually an available aftermarket actuator that does not have a NBS?

That's because it was a Plessey actuator and they are no longer manufactured or supported. The "retrofit" is an Eaton actuator. 

[1980Mooney]

8 minutes ago, PT20J said:

That's because it was a Plessey actuator and they are no longer manufactured or supported. The "retrofit" is an Eaton actuator. 

Good point.  I mis-read the parts notes.

560254 -507 was originally made by GEC (Plessey) as 880037-507.   Then Eaton made it.  Confusing.

I also had the parts notes highlighted wrong but fixed with edit.

Edited February 3, 2023 by 1980Mooney

[toto]

7 minutes ago, PT20J said:

That's because it was a Plessey actuator and they are no longer manufactured or supported. The "retrofit" is an Eaton actuator. 

Blech.  It's kind of hard to see how this "retrofit" is a solution to the NBS problem.  You're trading one actuator with a single point of failure for another actuator with a single point of failure.

[1980Mooney]

1 hour ago, PT20J said:

Do you know if that incident involved a Plessey or an Eaton actuator?  I know that Mooney was using both well into the 1990s and the accident reported by @1980Mooney(NTSB Accident Number ERA22LA319) involved a Plessey actuator with only 427 hours since spring replacement. Plessey and Eaton are similar but different designs. Plessey calls the spring a torsion spring and Eaton calls it a no-back spring. Mooney has taken to just referring to both as no-back springs. They may or may not be identical parts -- probably not.

The original service instruction M20-52 from 1/15/92 listed 2 failures of springs in Plessey actuators at 1200 and 1500 hours respectively. It included GEC/Plessey service instruction SI-11 requiring replacing the spring every 1000 hours. This appears to be the origin of the 1000 Hour replacement interval. I found two additional SDR reports of failures of Plessey actuators (one a broken spring and the other of undetermined cause, but likely the spring from the description). With the accident cited above, that makes at least 4, maybe 5, Plessey spring failures.

Service bulletin M20-266A cites a single failure of an Eaton spring and lists a limited number of aircraft that require removal of the Eaton actuator and it's return to Eaton. This is likely the source of the idea that it was a problem related to a particular lot of springs.

Subsequently, Eaton issued service instruction SI102000-901-1 that called for inspection of ALL actuators within 100 hrs and recommended replacement of the spring at 1000 hour intervals. Mooney published this as service bulletin M20-279. Apparently, all these bulletins and instructions were causing confusion so Mooney issued a comprehensive consolidated version as M20-282A. 

So, after all the dust settles, as of 9/22/2004 (the issue date of M20-282A), Mooney has only noted the failure of ONE Eaton actuator spring, which may have been limited to one lot of actuators, whereas 4 or 5 Plessey actuators are known to have suffered spring failures.

So, I would be concerned if I had a Plessey actuator because of the several documented failures, but I'm not so sure that the Eaton's are much of a problem. It would be nice if Mooney would publish the actual number of failures of each type.

Skip

 

Hard to say.  The report by the FAA in 2003 lacks detail.  The Mooney M20R & M20S Parts Catalog shows the Eaton actuator first and the GEC (Plessey) as the alternate.

 

FAA Accident and Incident Reporting System (AIDS)

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GENERAL INFORMATION

Data Source	ACCIDENT AND INCIDENT DATABASE
Report Number	20031030030799I
Local Date	30-OCT-03
City	TOMS RIVER
State	NJ
Airport Name	ROBERT J. MILLER AIR PARK
Event Type	INCIDENT
Mid Air Collision	NOT A MIDAIR

 

AIRCRAFT INFORMATION

Aircraft Damage	MINOR
Aircraft Make	MOONEY
Aircraft Model	M20S
Aircraft Series	NO SERIES EXISTS
Airframe Hrs	960
Primary Flight Type	PERSONAL
Secondary Flight Type	PLEASURE
Type of Operation	GENERAL OPERATING RULES
Registration Nbr	2234X
Total Aboard	2
Fatalities	0
Injuries	0
Aircraft Weight Class	UNDER 12501 LBS
Number of Engines	1

 

Environmental/Operations Info

Primary Flight Conditions	VISUAL FLIGHT RULES
Secondary Flight Conditions	WEATHER NOT A FACTOR
Flight Plan Filed	UNKNOWN

 

Pilot In Command

Pilot Certificates	COMMERCIAL PILOT
Pilot Rating	AIRPLANE SINGLE, MULTI-ENGINE LAND
Pilot Qualification	QUALIFIED
Flight Time Total Hours	1597
Total in Make/Model	689
Total in Last 90 days	64

 

Event Remarks

(-23) LANDING GEAR WOULD NOT EXTEND. PILOT LANDED AIRCRAFT GEAR UP. AIRCRAFT RECEIVED MINOR DAMAGE TO THE BELLY PAN, BOTH NOSE GEAR DOORS, AND PROPELLER. THE AIRCRAFT WAS JACKED AND THE GEAR WAS TESTED IN NORMAL AND EMERGENCY SYSTEMS. GEAR WOULD NOT MOVE IN EITHER POSITION. DISCONNECTED GEAR LINKAGE FROM THE LANDING GEAR ACTUATOR AND THE GEAR FREELY MOVED TO THE DOWN POSITION. DISASSEMBLED THE LANDING GEAR ACTUATOR. FOUND THE TABS HAD BROKEN OFF THE NO BACK CLUTCH SPRING PREVENTING THE GEAR FROM MOVING IN EITHER NORMAL OR EMERGENCY POSITION.

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END REPORT