No back spring in landing gear actuators

[nels]

1 hour ago, teejayevans said:

What if the engine had 4000 hrs vs 10?

I'd like to know how much stress,flex the spring goes under, then I could make an educated decision.

Not really a fair comparison but to answer that question I would feel more comfortable with putting another 200 hrs on the 4000 hr engine than putting the first 200 on the ten hour overhauled engine.

[fantom]

On Saturday, April 16, 2016 at 6:53 PM, jetdriven said:

Bluehighwayflyer's 201 has like 8k on the back clutch spring, still going fine.

MTBF probably 30,000 hours.

[Steveolyo]

Friday the gear would not come up during a routine flight in a '69 M20F. The breaker popped. I pushed it in. The gear came up. 

Later I was on a long final, trying to get the gear down. Breaker popped. Gear would not go down. I declared an emergency, I pulled the cable handle and fortunately the gear came down after quite a few pulls. I flew by the tower at SLC international and they confirmed my gear was down. I cancelled the emergency, landed without incident and went to the hangars to check the electric gear. Instead of a Duke I found a Plessey .

No parts are available for this beauty which logbooks documented being changed out in 1991,  25 years ago and with over 1000 hours usage. Bummer.

I am ordering a rebuilt Eaton to replace it. I could nurse it along with a new motor, but it had started making noise when I had the plane on Jacks. Sort of a chatter noise during deploy at about 70% - 90% so I'm glad it didn't have the famous spring of terror break. 

I may have a gear up landing some day because of failed landing gear, if I do have one it won't be due to keeping a known problematic actuator.

[Marauder]

On your 69 you don't have a crank? You described it as a "pull". I thought the floor mounted pull string emergency extension were limited to the J models on.

Sent from my iPad using Tapatalk

[Ron McBride]

My 69F is the Dukes, with the crank on the wall.   Not fun to use, fortunately have only used for practice/maintenance while doing the annual.   I have replaced the gears though, and had the 40:1's installed.

Ron

[Steveolyo]

The '69 had a crank and a Dukes, but for some reason the actuator was changed in '91 as documented in the logbook. It was changed to the accursed Plessey. Probably because the Dukes failed, or to get rid of AD 75-23-04 which is a bit of work, probably the hardest part is the 200 hour removal of the actuator, disassembly of the actuator, cleaning all the grease out of the actuator, inspecting the gears, regreasing, and reinstalling. So maybe the previous owner was convinced that he might as well put in the plessey because it was at the time , an upgrade. More information on that AD can be found in Don Maxwells article: http://www.donmaxwell.com/publications/MAPA_TEXT/AD%2075-23-04_Dukes/AD75-23-04%20Dukes.htm

 

[Awqward]

Ok, my J is just about to have had "actuator or whatever" opened up and the no back Spring inspected as it has never been done after 3k hours.   Also the emergency gear ratchet no longer works and just clicks away and does not engage so we are looking at that as well.  Interestingly:-

if the release cable is not rigged correctly (that is connected to the red emergency cover on the gear) the cog will be damaged during the normal cycle.  Mine was found to have failed in the annual so it is really annoying, but better it was found on the ground rather than in the air when it was needed.

ill let you all know how many hours it takes etc and what we do to fix it etc.

andrew

Yes, as I talk about earlier in this thread, the brass clutch design whereby it relies on the correct tension in the cable to the red handle, is not great.... Good that you caught it at annual....like I did.

[Yooper Rocketman]

I am in annual and we pulled the emergency gear system off the gear motor (had to drop the motor to access the top two bolts) and performed the 1,000 hour clean, grease and readjustment of the cable springs (and lock in/out cable).  I had found the emergency gear cable would not fully retract every time after being pulled.  The procedure is pretty straight forward in the manual, but getting the right tension for full recoil without bottoming out the the springs was a little tedious.

Tom

[carusoam]

Brass is a soft metal...  Odd choice for a precise part.  Hammered out of shape, just once and it no longer functions properly.

Best regards,

-a-

[kortopates]

Brass is a soft metal...  Odd choice for a precise part.  Hammered out of shape, just once and it no longer functions properly.

Best regards,

-a-

Brass makes good sense when you consider the clutch needs to be sacrificed in lieu of damaging the electric gear if it becomes mistakenly or unknowingly engaged (by typically a rear seat pax). then when the pilot goes to retract the gear electrically and the binding caused gear actuator CB to pop damage should be limited to chewing up the clutch a bit rather than the gear. See post in the annual thread for more details if desired.

Sent from my iPhone using Tapatalk

[Cyril Gibb]

3 hours ago, kortopates said:

Brass makes good sense when you consider the clutch needs to be sacrificed in lieu of damaging the electric gear if it becomes mistakenly or unknowingly engaged (by typically a rear seat pax). then when the pilot goes to retract the gear electrically and the binding caused gear actuator CB to pop damage should be limited to chewing up the clutch a bit rather than the gear. See post in the annual thread for more details if desired.

Sent from my iPhone using Tapatalk

Unfortunately, according to the wiring diagrams I've been perusing, Mooney kept the actuator 15 amp circuit breakers for some years after going to 28 volt systems before reducing them by half.  Doubling the power to the actuator meant that poor rigging or travel limits would not be detected by the circuit breaker until mechanical failure occurred.  I've wondered why a circuit breaker amp reduction wasn't in a SB or AD.

[M20S Driver]

I used to drop the gear at 130 kts range (max is 140 per POH) to slow down and get a nice rate of decent.  My mechanic ( top notch mechanic and professional turbine pilot) thinks that it is too fast and the gear should be lowered  around 110 kts.  In his opinion, higher speed puts too much load on the motor and no-back- spring.  

What speed should be used as a normal target to lower the gear in a long body and at what speed do you normally do it?

Just a Driver

[carusoam]

Following the POH should be pretty good for the Long Body.  The documents were pretty well sorted out by the 90s.  The landing gear had a few years and multiple renditions to stabilize. The PFM was not beefy enough.  Then the Bravo went first for ultra-modern Mooneys, then O, then the Eagle...

The C took less effort to lower the gear, the faster you were going... Measurable by the stress on the Armstrong motor.

Other than follow the POH and placard, I have no guidance to pull from.

That is one of the best reasons for having comfort with my factory built airplane.  Me and another couple thousand Long Body pilots using the same system...

Best regards,

-a-

[donkaye]

17 minutes ago, M20S Driver said:

I used to drop the gear at 130 kts range (max is 140 per POH) to slow down and get a nice rate of decent.  My mechanic ( top notch mechanic and professional turbine pilot) thinks that it is too fast and the gear should be lowered  around 110 kts.  In his opinion, higher speed puts too much load on the motor and no-back- spring.  

What speed should be used as a normal target to lower the gear in a long body and at what speed do you normally do it?

Just a Driver

These are certified airplanes and as such there are safety factors that must be used in the design.  If the maximum gear down speed is 140 knots in the POH, then that is what I will use.  These are performance airplanes not Cessnas.  I have over 3600 hours on my Bravo, am on my second engine, and follow the book on maintenance including replacing the backspring at 1,000 hours.  Tell your mechanic he should get some Mooney instruction.

[N9453V]

40 minutes ago, donkaye said:

These are certified airplanes and as such there are safety factors that must be used in the design.  If the maximum gear down speed is 140 knots in the POH, then that is what I will use.  These are performance airplanes not Cessnas.  I have over 3600 hours on my Bravo, am on my second engine, and follow the book on maintenance including replacing the backspring at 1,000 hours.  Tell your mechanic he should get some Mooney instruction.

There are some MSC's that feel the 1000 hours is excessive and instead listen for chattering. Mine finally exhibited that chattering after 12 years and 2500 hours since last spring replacement so I just had it replaced this annual (for the Avionics Products actuators it's now $802).

-Andrew

[M20S Driver]

Top Gun originally (2013) was waiting for Mooney to increase the time to 2000 hours.  They are now recommending to replace it at 1000 hours.   

Perhaps the chattering is the best near failure indicator for a seasoned pilot but not everyone knows or understands it.

[donkaye]

4 minutes ago, bluehighwayflyer said:

Top Gun left my original NBC spring in service for 3500 hours and I replaced it a second time after an additional 6500 hours.  YMMV. 

Each person chooses the level of risk with which they are comfortable.  A back spring failure is a single point of failure and the gear won't come down or go up with ANY procedure.  It's going to be a gear up landing.  Do you really want to risk family or innocent friends who don't know any better when they go flying with you over a 1 AMU cost?  My answer is an emphatic NO.

[M20S Driver]

Just now, bluehighwayflyer said:

My answer is no, too. I replaced the NBC spring approximately 300 hours ago. 

Yes.  I had the same discussion with Mark and Tom and decided to replace it and I am glad I did.  

I will not fly an airplane with damage history such as a gear up landing (OK, this is my personal choice and I have heard long arguments about it) so it is a small fee to pay to have a better chance of not having a no back spring failure and looking for another plane.

[N9453V]

28 minutes ago, donkaye said:

Each person chooses the level of risk with which they are comfortable.  A back spring failure is a single point of failure and the gear won't come down or go up with ANY procedure.  It's going to be a gear up landing.  Do you really want to risk family or innocent friends who don't know any better when they go flying with you over a 1 AMU cost?  My answer is an emphatic NO.

The data I've seen is that most (if not all) spring failures occurred from the single bad batch where the ends were bent after heat treating instead of before. As well, those failures were all in the down position. I have also seen anecdotal evidence of cases were the spring was replaced improperly and a gear up landing subsequently happened. This is unlikely though, for those of using a reputable MSC.

If an aircraft is using for flight training and doing touch and go's all day, I'd agree that 1000 hour replacement is probably a good idea, but I think it's a hard case to argue that waiting to 2000 hours is a greater risk especially with the risk of maintenance-induced failure.

Also, a gear up landing properly executed rarely results in any injury. In a Mooney, that's a new prop, engine goes back to Lycoming/Continental, new step and a new smooth belly. Not much of a big deal so long as the aircraft is properly insured.

 

10 minutes ago, M20S Driver said:

Yes.  I had the same discussion with Mark and Tom and decided to replace it and I am glad I did.  

I will not fly an airplane with damage history such as a gear up landing (OK, this is my personal choice and I have heard long arguments about it) so it is a small fee to pay to have a better chance of not having a no back spring failure and looking for another plane.

Why's that? I've seen Don Maxwell's work repairing geared up airplanes and there is no difference as far as I can tell.

[M20S Driver]

23 hours ago, N9453V said:

Why's that? I've seen Don Maxwell's work repairing geared up airplanes and there is no difference as far as I can tell.

There are too many variables in the repair of the gear up damage to make it as good as new.  Don Maxwell is great but he is over a 1000 miles away from me and the whole repair process is very time consuming.

[N9453V]

20 minutes ago, M20S Driver said:

There are too many variables in the repair of the gear up damage to make it as good as new.  Don Maxwell is great but he is over a 1000 miles away from me and the whole repair process is very time consuming.

Which variables are you referring to? New prop, engine overhauled/inspected as good as new, new smooth belly, new step, new antennas... I'm curious which part or parts you feel cannot be repaired to the same level as when it left the factory.

My plane had a gear up and a prop strike before I bought it and there is no way to tell unless you read the logbooks and see that the repairs were done by Dugosh.

-Andrew

[mike_elliott]

On ‎6‎/‎1‎/‎2016 at 11:12 PM, M20S Driver said:

I used to drop the gear at 130 kts range (max is 140 per POH) to slow down and get a nice rate of decent.  My mechanic ( top notch mechanic and professional turbine pilot) thinks that it is too fast and the gear should be lowered  around 110 kts.  In his opinion, higher speed puts too much load on the motor and no-back- spring.  

What speed should be used as a normal target to lower the gear in a long body and at what speed do you normally do it?

Just a Driver

Raising the gear at higher speeds will put more strain on the system than lowering it. The mechanism is basically the same on the manual J bar planes, If you were to fly one of them, you would find the gear lowers very easily at higher speeds and is a bi*ch to retract at higher speeds. The gear speed lowering limitation is in part for the gear doors, especially in transit.

[M20S Driver]

On 6/2/2016 at 10:33 PM, N9453V said:

Which variables are you referring to? New prop, engine overhauled/inspected as good as new, new smooth belly, new step, new antennas... I'm curious which part or parts you feel cannot be repaired to the same level as when it left the factory.

My plane had a gear up and a prop strike before I bought it and there is no way to tell unless you read the logbooks and see that the repairs were done by Dugosh.

-Andrew

Assuming that the gear up had minimal repairable airframe damage, I would be comfortable with with a new engine, Prop, and engine mount to have a piece of mind.  Keep in mind that this is my personal opinion and you are not the only one disagreeing with this  

My opinion would have had some flexibility if I flew in the flat lands.  I regularly fly over the Sierras and can not take any chances.

[N9453V]

6 hours ago, M20S Driver said:

Assuming that the gear up had minimal repairable airframe damage, I would be comfortable with with a new engine, Prop, and engine mount to have a piece of mind.  Keep in mind that this is my personal opinion and you are not the only one disagreeing with this  

My opinion would have had some flexibility if I flew in the flat lands.  I regularly fly over the Sierras and can not take any chances.

If you can't take any chances over the Sierras, you should probably upgrade to something with twin turbine engines. Even the best maintained single-engine aircraft can experience engine failure (although the chance is less than 1 in 50,000 hours).

I routinely fly over the Rockies between Seattle and Calgary, so I share your concern for flight safety, but you're not going to be able to convince me that a overhauled/repaired engine by a reputable shop, new prop and inspected/magnafluxed engine mount is less safe than going all new without data to backup your claims.

-Andrew

Edited June 10, 2016 by N9453V

[Awqward]

 IF YOUR CABLES AND SPRING ARE NOT CORRECTLY ADJUSTED YOU WILL GET A BUGGERED CLUTCH ALMOST INSTANTLY.  Make sure it is checked every 100 hours. (watch the engineer do it if necessary, it is cheaper than fixing it belive me!)

.

Excellent photo diary Hyett6420.... It is worth noting that my mechanic (or engineer as you say in the UK) managed to remove and replace the emergency extension clutch without the need to remove the entire gearbox from the airplane. It can be done by removing only the ratchet housing...whole thing took around 2 hours IIRC.

Sent from my iPhone using Tapatalk