No Back Spring for GEC Plessey actuator in ‘85 M20J

[Sabremech]

36 minutes ago, philip_g said:

I have no idea how the pma process works but my co-owner can get quality springs made in Japan easily if the specifications are laid out.

It doesn’t make it impossible but much harder for me to do a supplier audit every year. Local is the way to go if I find someone near me capable of manufacturing them. 
David

[PT20J]

David @Sabremech, you might want to check out https://reell.com/products/clutch-torsion-spring-manufacturers

Skip

[Jetrn]

I would purchase one to put on the shelf in the hanger.

[Sabremech]

40 minutes ago, PT20J said:

David @Sabremech, you might want to check out https://reell.com/products/clutch-torsion-spring-manufacturers

Skip

Thanks much. Will add them to my possible source list if I proceed.

David

[Sabremech]

5 hours ago, philip_g said:

I know it's been the holidays and all but this came to mind today. Any advances @Sabremech

I haven’t advanced with this project as of yet. I’ll make contact with the folks who said they had some old springs for me to possibly use for the reverse engineering.

Thanks,

David

[bmcconnaha]

On 1/3/2022 at 5:15 PM, Sabremech said:

I haven’t advanced with this project as of yet. I’ll make contact with the folks who said they had some old springs for me to possibly use for the reverse engineering.

Thanks,

David

David,

Any update on this? 

[Sabremech]

6 hours ago, bmcconnaha said:

David,

Any update on this? 

Hi bmcconnaha,

I’m still not sure if I’m going to proceed with this project. I don’t know if I want to do anymore FAA/PMA parts at least right now while the FAA are still working from home due to Covid restrictions for them. I’m still waiting on a call back from them on an MEL and LOA’s for my full time job. It’s almost impossible to get anything done in a timely manner right now.

Thanks,

David

[bmcconnaha]

Just now, Sabremech said:

Hi bmcconnaha,

I’m still not sure if I’m going to proceed with this project. I don’t know if I want to do anymore FAA/PMA parts at least right now while the FAA are still working from home due to Covid restrictions for them. I’m still waiting on a call back from them on an MEL and LOA’s for my full time job. It’s almost impossible to get anything done in a timely manner right now.

Thanks,

David

Yeah, I understand that.  I had to really bug to get a ferry permit in a timely fashion last year.  
being that the plessey is no longer supported, wouldnt this qualify as an owner produced part? 

[Sabremech]

10 hours ago, bmcconnaha said:

Yeah, I understand that.  I had to really bug to get a ferry permit in a timely fashion last year.  
being that the plessey is no longer supported, wouldnt this qualify as an owner produced part? 

This one might have a bit too much liability for me to want to make it owner produced. 

[bmcconnaha]

3 hours ago, Sabremech said:

This one might have a bit too much liability for me to want to make it owner produced. 

Did you ever get your hands on a used plessey spring? If you don’t want to advance the project and have the spring, I’d be willing to have it analyzed by a spring company and get the specifics at my own expense.  Then those could be passed on to other owners that need it and they could have their own made.   Lasar has no reconditioned units.  They are quoting new units for 27k.  This would greatly help the people left with the plessey units.  Crazy how our birds still have a manufacturer that hasn’t completely shut down, and if you compare stuff like this to a Piper Comanche, that’s been out of production for fifty years, lots of Comanche stuff is easier to come by.  

[Larry]

There is an Avionics Products actuator on Fleabay now for $4200/offer.  It has a 12 volt motor, but that can be changed.  Even with a new spring, changing the motor, it still far less than 27K.

[Sabremech]

8 hours ago, bmcconnaha said:

Did you ever get your hands on a used plessey spring? If you don’t want to advance the project and have the spring, I’d be willing to have it analyzed by a spring company and get the specifics at my own expense.  Then those could be passed on to other owners that need it and they could have their own made.   Lasar has no reconditioned units.  They are quoting new units for 27k.  This would greatly help the people left with the plessey units.  Crazy how our birds still have a manufacturer that hasn’t completely shut down, and if you compare stuff like this to a Piper Comanche, that’s been out of production for fifty years, lots of Comanche stuff is easier to come by.  

I did not get any of the springs. Someone was working on that on my behalf but I’ve not received anything. 
Thanks,

David

[Tx_Aggie]

On 11/4/2021 at 3:24 AM, spayne59 said:

Our no back spring is worn and we need another, AOG.  Actuator is the Plessey type and is not the same spring as in other   J models.  I can’t find one anywhere! Can anyone help?

What is this and does it do?

[PT20J]

The Mooney electric gear is retracted and lowered by a motor-driven ball screw (a low-friction version of a jack screw where the threads ride on ball bearings). The no-back spring is the key component of a braking mechanism that keeps the weight of the retracted gear from back driving the ball screw since there are no mechanical up locks.

Skip

[1980Mooney]

Another way to to describe it is it keeps the gear up once retracted. From MooneyFlyer: page 17

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

”The No-Back Clutch Spring
These newer models have a common problem with the no-back clutch spring, which is recommended to be changed every 1,000 hours of aircraft time. A no-back clutch spring is what keeps the gear up when retracted. It keeps the gear from unwinding after the gear up switch shuts off the power.
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. A later problem we have found on the Eaton actuators is chipping of the jack screw. While difficult, I have been able to buy a new jack screw. I don't know current prices, but I do know that a new actuator is well over $10,000.
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. Another problem with the newer actuators is the wear on the emergency extension cable. It is Teflon coated and the Teflon can tear and peel loose and that loose Teflon can actually jam the actuator. It actually happened during a practice emergency landing gear extension.”

 

[Tx_Aggie]

22 minutes ago, 1980Mooney said:

Another way to to describe it is it keeps the gear up once retracted. From MooneyFlyer: page 17

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

”The No-Back Clutch Spring
These newer models have a common problem with the no-back clutch spring, which is recommended to be changed every 1,000 hours of aircraft time. A no-back clutch spring is what keeps the gear up when retracted. It keeps the gear from unwinding after the gear up switch shuts off the power.
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. A later problem we have found on the Eaton actuators is chipping of the jack screw. While difficult, I have been able to buy a new jack screw. I don't know current prices, but I do know that a new actuator is well over $10,000.
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. Another problem with the newer actuators is the wear on the emergency extension cable. It is Teflon coated and the Teflon can tear and peel loose and that loose Teflon can actually jam the actuator. It actually happened during a practice emergency landing gear extension.”

 

Is this on all models with electric gear? 

[1980Mooney]

19 minutes ago, Tx_Aggie said:

Is this on all models with electric gear? 

This may help. There were several manufacturers of electric

https://www.knr-inc.com/25-shoptalk/30-200107-emergency-gear-extension-systems