Good, not great landing

[mooniac15u]

14 hours ago, M20Doc said:

Mike,

You must be referring to S/I M20-88.  Here is the opening lines

SUBJECT: STABILIZER TRIM STOP/SCREW MODIFICATION

MODEL/S/N AFFECTED:

TIME OF COMPLIANCE: INTRODUCTION:

M20J - S/N 24-0001 THRU 24-1694 & 24-3000 THRU 24-3172 M20K - S/N 25-0001 THRU 25-1230
M20L - S/N 26-0001 THRU 26-0041
M20M - S/N 27-0001 THRU 27-0058

AT OWNERS DISCRETION

There have been occasions when the elevator trim control wheel has been manually turned to the extreme nose up or nose down condition and the electric trim system was unable to move the trim indicator nut off the stop at the next electrically activated command. Manual movement must be the initial action to get the trim indicator nut off the stop, then the electrical system will operate normally.

If an aircraft owner has experienced this situation in his routine habits of operation, the incorporation of this Ser- vice Instruction may be desired. 

 

Clarence

So, it is the trim indicator that is getting jammed rather than the trim itself?

[ArtVandelay]

4 hours ago, M20Doc said:

...their engines cost less to operate and overhaul and they're flown by pilots not driver.  

No way...definitely less avgas, and I don't see how my 4 cylinder costs more to overhaul? Or are you referring to one of the turbo variants?

[Ron McBride]

4 hours ago, M20Doc said:

I've heard that as well. Some even say that a Comanche will carry more weight, they can even fly off grass, they don't ever need fuel tank re sealing, they cruise faster, their engines cost less to operate and overhaul and they're flown by pilots not driver.  

But you'll never hear me say these things on a Mooney site.

Clarence

A good friend has a Comanche 250, I have been in it many times.  It is a little wider than my F.  The seats are not very comfortable, in front or back.   Weights are very similar, and it could be a couple of knots faster, but the fuel burn to do it, no thanks.  When we race, I want both planes at 10 gallons an hour, he says "no way". 

It was a great plane to move me around while mine was in annual, getting painted etc.

Ron

[Bob_Belville]

10 minutes ago, teejayevans said:

No way...definitely less avgas, and I don't see how my 4 cylinder costs more to overhaul? Or are you referring to one of the turbo variants?

He's pulling your chain - Mooney envy - ignore Clarence. (Only on the subject of Comanches.) When Avgas hits 2.00 CD per litre a certain PA24-400 will be for sale.

[Guest]

1 hour ago, Bob_Belville said:

He's pulling your chain - Mooney envy - ignore Clarence. (Only on the subject of Comanches.) When Avgas hits 2.00 CD per litre a certain PA24-400 will be for sale.

Its been that high before, it won't be for sale.

Clarence

 

[Guest]

1 hour ago, teejayevans said:

No way...definitely less avgas, and I don't see how my 4 cylinder costs more to overhaul? Or are you referring to one of the turbo variants?

Comparing the most produced Comanche (250) to the most produce Mooney (201)

From Van Bortel  IO-360A3B6D  $31785.00, cylinders 2153.00

                            0-540A1D5  $ 30828.00  cylnders 1131.00

As to fuel burn, KSKY to KLEE, 5:30 on 55 gallons

Clarence

[Guest]

3 hours ago, mooniac15u said:

So, it is the trim indicator that is getting jammed rather than the trim itself?

Sort of.  The trim gear box stops below the floor jamb,  the S/I replaces the stop nuts.

Clarence

[Guest]

1 hour ago, N803RM said:

A good friend has a Comanche 250, I have been in it many times.  It is a little wider than my F.  The seats are not very comfortable, in front or back.   Weights are very similar, and it could be a couple of knots faster, but the fuel burn to do it, no thanks.  When we race, I want both planes at 10 gallons an hour, he says "no way". 

It was a great plane to move me around while mine was in annual, getting painted etc.

Ron

Your freinds Comanche needs a visit to my shop.  A good 250 should do 160-165 KTAS.

Clarence

[Ron McBride]

I have a fast F.  If I takeoff before him on a 1hour trip, I will be landing behind him.  

Ron

[cnoe]

On 11/30/2016 at 9:35 AM, DVA said:

I bet if you pull the A/P breaker you will have no electric trim.

 

On 11/30/2016 at 9:41 AM, Hyett6420 said:

this is true, and I have done in the past.

 

On 11/30/2016 at 10:11 AM, cnoe said:

 

Hmmmmmm. Maybe I'll learn something today. I wouldn't have thought this to be the case but will check on it soon.


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On 11/30/2016 at 0:00 PM, cnoe said:

True, but the Klixon switch that controls my electric trim system has an integral breaker. Additionally it's still functional if my AP is turned off. So I never considered that the AP "breaker" would affect the trim system. It might; sounds like it does for some planes. Always learning. I'll report my findings here once I know.

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Okay, following up on this...

My J's autopilot and electric trim systems were both installed when the plane was delivered new in 1978.

Testing yesterday confirms that the electric trim is not interconnected with the AP system. You can pull the AP breaker out and the ET still works fine. In the event of a runaway ET the only way to disconnect the ET is to turn off the Klixon switch/circuit-breaker on the panel.

OTOH, the Altitude Hold system (which was added more than a decade later) has an interconnect and will not engage without a reference signal from the AP.

So, in my plane a trim malfunction first requires overcoming the control forces then immediately turning off the Klixon switch just above the throttle.

Yours may differ.

[Amelia]

Deliberations on just what to do with my poor airplane continue. Apparently it will be close, whether to total it or fix it. Sigh...

Of more general interest, maybe, is that Mooney brass have become significantly interested in this jammed trim issue, (I gather mine wasn't the first, by a ways, but they'd like it to be the last!) and will be, within the next few days, issuing a Service Bulletin discussing causes and preventative measures, updating and expanding the S/I M20-88.

[mike_elliott]

16 minutes ago, Amelia said:

Deliberations on just what to do with my poor airplane continue. Apparently it will be close, whether to total it or fix it. Sigh...

Of more general interest, maybe, is that Mooney brass have become significantly interest in this jammed trim issue, (I gather mine wasn't the first, by a ways, but they'd like it to be the last!) and will be, within the next few days, issuing a Service Bulletin discussing causes and preventative measures, updating and expanding the S/I M20-88.

Mimi, Do you know what additional preventative actions will be added to it to mitigate the potential issue further? Did yours jam because the original SI m20-88 was not done, or did it jam after completing the modification of SI M20-88? It has been around since 1990, and I would have thought most of the fleet would have complied with it by now.

I hope that all comes out well for you, and you are airborne once again soon! You and Rob have become a fixture at the Mooney Summit!

[Amelia]

Oddly, Mike, it appears that it was never done, because the two surfaces that jammed together were flat rather than convex, and quite dry, despite having been greased only 7 months earlier, after s similar complaint that didn't result in undue drama. Nobody mentioned the s/i to me in all these years. (Fume. A good case for MSCs?) it would be nice if nobody else gets to have this much fun.

[Hank]

Oh, poor Marvin! Hope you will be back again soon, Mimi.

At least we're moaning the possible loss of a plane and not two people . . . Gotta keep things in perspective!

Addressing your last question, is there an easy way to get a list of all applicable SI & SBs and root through the logs to see which have been done?

[Yetti]

So after spending some quality time lubing trim things.   The trim indicator is a separate acme screw that live alongside the trim wheel.  With full up my trim indicator was about a half inch off the rear end of travel. Did not check full down, but I am going to. The trim wheel goes into a right angle gear box and is connected via a roller chain.  Like on your bicycle but smaller think it would be a #10 size. 

 I will go over to the airport and take some pictures.   I would think the jack screw in the rear of the plane would have more limits than the trim indicator.   I would also think there are stops on the hinge itself.   One thing that not sure if it could happen if you straighten out the hinge that would be really hard to get to flex again.

Interesting note is that you can turn with very light finger pressure the control rods that go to the back of the plane when everything is lubed properly.

there are a fair amount of universal joints in the rods that turn the jack screw in the rear of the plane.

As I recall from a prior discussion there is also a friction adjustment up on the trim wheel itself.

cleaning the what I am sure is 40 year old grease off the roller chain it is crazy interesting how hard the grease has become.   there was some excess grease that was on the side of the right angle drive.   It was like glue and had to pry it off the aluminum surface with a screw driver.  It was absolutely not pliable at all

[Marauder]

So after spending some quality time lubing trim things.   The trim indicator is a separate acme screw that live alongside the trim wheel.  With full up my trim indicator was about a half inch off the rear end of travel. Did not check full down, but I am going to. The trim wheel goes into a right angle gear box and is connected via a roller chain.  Like on your bicycle but smaller think it would be a #10 size. 
 I will go over to the airport and take some pictures.   I would think the jack screw in the rear of the plane would have more limits than the trim indicator.   I would also think there are stops on the hinge itself.   One thing that not sure if it could happen if you straighten out the hinge that would be really hard to get to flex again.
Interesting note is that you can turn with very light finger pressure the control rods that go to the back of the plane when everything is lubed properly.
there are a fair amount of universal joints in the rods that turn the jack screw in the rear of the plane.
As I recall from a prior discussion there is also a friction adjustment up on the trim wheel itself.
cleaning the what I am sure is 40 year old grease off the roller chain it is crazy interesting how hard the grease has become.   there was some excess grease that was on the side of the right angle drive.   It was like glue and had to pry it off the aluminum surface with a screw driver.  It was absolutely not pliable at all

It'd be interested in seeing those photos.


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[Yetti]

So after spending some more time under a mooney with it's belly exposed.  A correction to the above the landing gear indicator is part of the drive chain to the jackscrew.   

I cranked the trim to the limits and really could not see it getting jammed at the stops unless something stripped.   I think the trim indicator is the upper and lower limit for the tail.  I cranked the trim fully up and fully down.  Based on the grease it had not been to one of the stops recently.   You can turn the trim down by hand using the drive line.  So pretty easy to do.  Cranking up is doable but easier with the trim wheel.

 

[Yetti]

One of the two bolts that hold the tail on.... which looks bigger than one of the 4 bolts that hold the engine mount on.

[Guest]

On December 15, 2016 at 0:07 PM, Amelia said:

Oddly, Mike, it appears that it was never done, because the two surfaces that jammed together were flat rather than convex, and quite dry, despite having been greased only 7 months earlier, after s similar complaint that didn't result in undue drama. Nobody mentioned the s/i to me in all these years. (Fume. A good case for MSCs?) it would be nice if nobody else gets to have this much fun.

I'm still confused.  Did the trim run away to the full up un commanded, or did you trim up and the system kept going when you released the trim button?

Clarence

[Guest]

1 hour ago, Yetti said:

One of the two bolts that hold the tail on.... which looks bigger than one of the 4 bolts that hold the engine mount on.

The two tail hinge bolts are 1/4" diameter, as are the engine mount to airframe bolts.

Clarence

[Cyril Gibb]

3 hours ago, Yetti said:

One of the two bolts that hold the tail on.... which looks bigger than one of the 4 bolts that hold the engine mount on.

I just looked in the parts manual.  I may be wrong (and often am), but the washers don't seem to be correct. The drawing in the manual shows a washer on either side of the centre unit that keeps the legs of the fork spread.  There's also a single washer indicated under the nut but not under the bolt head.  It may be camera angle, but the left leg looks bent in slightly.... washer missing?   ... and it looks dry and needing lube.

Maybe i've been hanging around Clarence too much during my owner assist.

[Yetti]

It got lubed after the picture.  I check the tail play on walk around.  I have found the little specs of orange silicone on lots of fasteners.  Does anyone know if this is something done at the factory?  I am guessing those bolts have not been touched since the factory put them there.

[cnoe]

Torque seal. Handy stuff, particularly on the nuts/studs of a dual-mag. Great for peace-of-mind. https://www.aircraftspruce.com/catalog/cspages/crosschecktorqueseal.php?clickkey=3836


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[Hank]

Yep that's all over our equipment at work. That way service techs can tell what  we've messed with.

[Guest]

3 hours ago, Cyril Gibb said:

I just looked in the parts manual.  I may be wrong (and often am), but the washers don't seem to be correct. The drawing in the manual shows a washer on either side of the centre unit that keeps the legs of the fork spread.  There's also a single washer indicated under the nut but not under the bolt head.  It may be camera angle, but the left leg looks bent in slightly.... washer missing?   ... and it looks dry and needing lube.

Maybe i've been hanging around Clarence too much during my owner assist.

It does indeed look to be bent/ pinched.  Mooney is famous for slipping washers between fitting.  Loosening the nut and bolt would be a good staring point to see if the fitting relaxes.

Clarence