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Flap control rod found during annual


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Hey guys.  Curious if anyone has seen this before.  My girl is in Annual this week.  Unfortunately I'm not able to be there, but my partner on the plane called and said the mechanic found a loose Flap Control Rod during annual.  He said that when they put the flaps down that it just "fell" out.  Scary thought that I was one flap operation from something bad happening.  Sorry I don't have much more info than this, but attached are the pictures I was sent.  It seems odd to me that a rod end bearing could back out when it's held captive in a control horn. :unsure:

Has anyone seen anything like this before?

IMG_4844.jpg

IMG_4845.jpg

IMG_4849.jpg

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IMG_4851.jpg

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I’m not sure I understand what happened. Are you saying that the rod end pulled out of the actuator when he pushed the flaps down?  Would be helpful to have a picture of the part that failed, where it failed. The pictures look like he just screwed the rod end back into the actuator. Was it replaced? Were the threads stripped? Rest assured you weren’t one flap deployment away from disaster. Losing the flap system is pretty low on the hierarchy of bad things that can happen...

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11 hours ago, bob865 said:

Hey guys.  Curious if anyone has seen this before.  My girl is in Annual this week.  Unfortunately I'm not able to be there, but my partner on the plane called and said the mechanic found a loose Flap Control Rod during annual.  He said that when they put the flaps down that it just "fell" out.  Scary thought that I was one flap operation from something bad happening.  Sorry I don't have much more info than this, but attached are the pictures I was sent.  It seems odd to me that a rod end bearing could back out when it's held captive in a control horn. :unsure:

Has anyone seen anything like this before?

IMG_4844.jpg

IMG_4845.jpg

IMG_4849.jpg

IMG_4850.jpg

IMG_4851.jpg


That sounds terrible…  possible flight control issue…

And I’m not seeing the issue in the pics…

 

So… let’s invite @M20Doc to have a look… (flap control rod issue)

 

PP thoughts only, not a mechanic…

Best regards,

-a-

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1 hour ago, M20Doc said:

I’m not sure where the issue with the flap rod end bearing is?  Looking at the trim torque tube, where is the wear sleeve?

Clarence

814ADAD0-5E12-4269-8D50-6E71FC172FA8.jpeg

Looks like there’s a piece of grommet edging there. I think I can see where it is split. I don’t remember what my airplane looks like. Is there supposed to be a guide block there? My vintage IPC does not make it as clear as it could be.

47F7AE07-C7DB-4DAF-A799-F7DEC1A6BAA8.jpeg.56c2e67262f9b8a2c6fb1a0a548d0a58.jpeg

Edited by Shadrach
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24 minutes ago, Shadrach said:

Looks like there’s a piece of grommet edging there. I think I can see where it is split. I don’t remember what my airplane looks like. Is there supposed to be a guide block there? My vintage IPC does not make it as clear as it could be.

47F7AE07-C7DB-4DAF-A799-F7DEC1A6BAA8.jpeg.56c2e67262f9b8a2c6fb1a0a548d0a58.jpeg

Most have a black heat shrink type of material slid over the aluminum tube as further wear protection.

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12 minutes ago, M20Doc said:

Most have a black heat shrink type of material slid over the aluminum tube as further wear protection.

My IPC doesn’t show that.  I’m pretty sure I haven’t seen nearly as many of these as you have. My belly pan will be coming off next week so I’ll get a look then.

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Sorry guys, I'm working off cryptic info myself.  Really wish I was there to take a look in person.  From what I understand is the rod end you see being installed in the picture Clarence re-posted had backed out of the actuator.  Seems to me, since the rod end is sandwiched in the control horn, the actuator has to be turning.  I'm not familiar with how that is built, but to me it seems like a linear actuator shouldn't be turning.

My partner on the plane is supposed to go down today and facetime me (I'm the technical one) so I can get a look at it and make sure what I'm telling you is right.

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13 hours ago, RLCarter said:

Agreed, jam nut is run all the way to the bearing, all the hardware (nuts, bolts & washers) looks like it’s been there a while 

If the jam nut was loose and the jack screw not well lubed (increasing friction) could the barrel rotate with the screw and disconnect from the heim bearing?

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6 minutes ago, PT20J said:

If the jam nut was loose and the jack screw not well lubed (increasing friction) could the barrel rotate with the screw and disconnect from the heim bearing?

It’s mechanical, it can fail just about anyway it wants….lol

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Folks continue to want to debate the time and cost of an annual.  I just spent 10 days doing not much more than cleaning, inspecting and lubricating as an owner in support of the mechanic (along with the other usual stuff).  There are a ton of rod ends, roll pins, jam nuts, jack screws, sprockets, chains, and guide blocks on this airplane.  I can't see anyone doing an annual in a day or two and doing a thorough job of inspection and lubrication.  Good catch here.  Would help to understand exactly what unscrewed from what.  Maybe I'll spend 11 day next time.  :>

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40 minutes ago, RLCarter said:

It’s mechanical, it can fail just about anyway it wants….lol

Touché.  Is there any service info about the actuator itself?  I'm digging but not finding anything. :( 

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2 hours ago, DCarlton said:

Folks continue to want to debate the time and cost of an annual.  I just spent 10 days doing not much more than cleaning, inspecting and lubricating as an owner in support of the mechanic (along with the other usual stuff).  There are a ton of rod ends, roll pins, jam nuts, jack screws, sprockets, chains, and guide blocks on this airplane.  I can't see anyone doing an annual in a day or two and doing a thorough job of inspection and lubrication.  Good catch here.  Would help to understand exactly what unscrewed from what.  Maybe I'll spend 11 day next time.  :>

First time annual, probably not. A well known aircraft with 10 previous inspections and a proactive owner that does not defer squawks? Two days is plenty for the inspection. I don’t know how long you’ve had your plane or what kind of environment it is operating. A Hangared airplane that flys 100 hours a year should not be that filthy if it’s reasonably oil tight and. If a panel hasn’t been off in 20 years than I would expect some pretty serious grime. There’s not a panel on my aircraft hat hasn’t been off in the last three years. More often than not, it looks pretty much like I left it.

It also helps to have reasonable expectations. Making something airworthy and making it pristine cannot be done in the same time frame.   If I’m hiring an A&P to make something airworthy that’s my expectation and no more. If I want more, I’ll ask for it and expect to pay accordingly. Replacing an alternator doesn’t mean that everything ahead of the firewall gets detailed. It doesn’t mean that anything gets detailed…I expect to have an operable alternator. I consider it a bonus if there are no fingerprints anywhere to be found after the job

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Landing with no flaps is a non event, not scary.

I was in a 767 Flying to Manchester UK that had a hydraulic failure. We landed with no flaps. It was a non event too.

I asked the Captain on the way out why he didn’t use the electric motor to put them down? He said that if the plane is landable, they won’t use any of the backup systems. 

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Scary… would be asymmetrical flap deployment…

With hand pumped flaps… the pilot has the opportunity to recognize this pretty quickly…

With motorized flaps… the pilot may get pretty surprised as the flap goes to the next setting…

 

The ailerons should be pretty good at offsetting the anomaly.

 

The annual is a great time to review all Rod ends… they are the working/wearing part of the system…

 

+1 for reviewing the plastic bits that keep the tubes from getting lathed…

 

My M20C was usually in the shop for four days for its annual…

PP thoughts only, not a mechanic…

Best regards,

-a-

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The RV7 had a similar electric actuator.  If the jam nut on the rod end became loose, it could allow the end of the linear actuator to rotate with the ballscrew.  Safety wire went around the pivot of the rod end, and through a hole in the end of the actuator to prevent rotation in case of a loose jam nut.  I'm shocked there could be a similar setup here, but looks like it.  If so, this would not be the first time.

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If I am seeing things correctly the concern is a fastener that came off of the flap actuator (hydraulic slave cylinder).

The good news about our Mooney flaps is that this failure mode should not cause flap asymmetry. I could see how that could be caused by a fastener backing out of one of the heim/rod ends on either side where the torque tube actuating both flaps is connected to each flap... there is a bearing there.

But I would add a note of caution... let us assume that you're coming to land, full flaps, on approach speed, and are properly trimmed. Putting the flaps down generates an aircraft nose down pitching moment that we counteract with nose-up trim. Now let us imagine the flap actuator was suddenly disconnected. Air load will blow the flaps up quite quickly. Now you're slow with a very abrupt aircraft nose UP pitching force. This can be counteracted with elevator but is still substantial.

An item for practice and some thought....

 

Edited by Immelman
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So I made it to the airport yesterday and got a full debrief...finally.  So hopefully I can fill in some blanks.

Per the mechanic, they had put the flaps down when they were preparing the plane for inspection.  They had stepped away to work on another plane when they heard the "thud" and the flaps fell all the way to the hard stop.  When the looked, they found the rod end was no longer connected to the actuator.  Since the rod end bearing couldn't rotate since it was bolted to the control horn, attention was directed to the actuator.  Further inspection revealed a set screw hole in the side of the actuator missing said set screw.  With the lost set screw it appears the actuator put enough back and forth torque on the rod end to loosen the jamb nut and allow it to turn.  Screw replaced, rod end in place, all tightened, rigging checked, and tested.  Obviously a system to keep an eye on for the foreseeable future.

Thanks to Clarence for spotting the trim control.  When we looked there is a plastic guide on the hole already for the wear plate.  The line seen in the pictures is just some polish, not a cut.  How a 40 yr old plastic ring is still in good shape is beyond me, but it was.

For a couple other points that came up.  I learned from this that the flaps are connected, so there is no possibility of asymmetric deployment which was my worry when I first heard.

The flap actuator for the 75 is electric, not hydraulic.

Since the failure was unexpected and not "before" a flap deployment, this still could have been a scary event.  Sure a no flap landing is non-event.  But what about a full flap landing that suddenly becomes a no-flap landing without any warning?  That's NOT a non-event.

Thanks to everyone for their feedback.  Will keep my eyes on this and let everyone know if anything changes.

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