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Nose Gear Truss Assembly Failure


TTaylor

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I wanted to post some details of the part failure we had recently. The "Truss Assembly, Retracting" on our 1975 F broke while the plane was being moved out of the maintenance hangar. This is the truss that is attached to the main noise gear truss.  The part broke at a primary weld and where the tube is cross welded to a second arm.  There is no rust in the breaks, so it is hard to tell if it was recent or long term.  This area can often be dirty on many older aircraft and ours should have been cleaned better.   Even though the engine was not running the damage could be potentially over $20K becasue we have a 3-blade prop and it may require an engine tear down. 

I would recommend that you clean all of the gear assemblies carefully each year and have your mechanic take the time to look carefully at these parts for any signs of cracks.   Below is a picture of what the complete assembly looks like and the picture from our broken part.

truss.jpg

Mooney truss.JPG

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35 minutes ago, RLCarter said:

E5BEC074-4CC9-4B91-BCB4-3CC2251D5C33.jpeg.fb9cf9f455c3f4f550872c0149096bc8.jpegThe area in the upper right looks like has been cracked for a while

That is grease where we accidentally put the parts back together after removal. The parts are being examined in the lab this week to see if anything can be learned about the break.

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Sorry you are having problems but I guess you were lucky it didn't break on landing or takeoff for that matter.  Is this the part that can be damaged by turning the nose wheel too far?  Was there any damage to the prop?  How do you know or who determines if the engine has to be torn down?  I will be cleaning and inspecting mine closer now.  Thanks

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1 minute ago, Htwjr said:

Sorry you are having problems but I guess you were lucky it didn't break on landing or takeoff for that matter.  Is this the part that can be damaged by turning the nose wheel too far?  Was there any damage to the prop?  How do you know or who determines if the engine has to be torn down?  I will be cleaning and inspecting mine closer now.  Thanks

This truss is not the one that can be hurt by turning the nose wheel too far.  It is attached to that one and sits just behind it.  Two of the propeller tips were slightly damaged when they hit the ground and both blades slightly bent back.  The prop is going in for a full overhaul. The gear doors will also need to be replaced. We must comply with the prop-stike AD even thought the engine was not running.  We are still evaluating if we will need/want to do a full engine tear-down.    We are consulting with our mechanic, the engine shop, and the partners about the tear down. 

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Sorry to hear.  Mine gets inspected once a year very carefully by Your Friendly Neighborhood Steingar.  I hand detail my airplane once a year, and that includes degreasing and carefully washing the nose gear assembly.  Hard not to give it a good look see when you're washing it. Got a little dent (I think I know where it came from too) but no cracks.  told my mechanic about the dent, he didn't seem overly concerned.

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39 minutes ago, TTaylor said:

This truss is not the one that can be hurt by turning the nose wheel too far.  It is attached to that one and sits just behind it.  Two of the propeller tips were slightly damaged when they hit the ground and both blades slightly bent back.  The prop is going in for a full overhaul. The gear doors will also need to be replaced. We must comply with the prop-stike AD even thought the engine was not running.  We are still evaluating if we will need/want to do a full engine tear-down.    We are consulting with our mechanic, the engine shop, and the partners about the tear down. 

AFAIK, the insurance typically covers the full tear down after something like this, right?

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1 minute ago, jaylw314 said:

AFAIK, the insurance typically covers the full tear down after something like this, right?

We are waiting to get a detailed response from the insurance company.  They will cover the full tear down.  They do not cover the part (truss) that broke and the propeller rebuild will be prorated over the actual hours versus TBO.  We have about 700 hours on the engine and propeller at this time.   The decision on if the engine should be torn down we have to decide what we are comfortable with.  Many would say that the insurance company is paying for it, so do it.  But with the engine not running and the relatively slow collapse of the front gear, does it really make sense to do?   We are asking the experts we know to help us decide.  If we decide to tear down, it will mean extra time to remove and ship the engine as well as adding an extra $8K t o $10K to the cost for the insurance company. 

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9 minutes ago, TTaylor said:

We are waiting to get a detailed response from the insurance company.  They will cover the full tear down.  They do not cover the part (truss) that broke and the propeller rebuild will be prorated over the actual hours versus TBO.  We have about 700 hours on the engine and propeller at this time.   The decision on if the engine should be torn down we have to decide what we are comfortable with.  Many would say that the insurance company is paying for it, so do it.  But with the engine not running and the relatively slow collapse of the front gear, does it really make sense to do?   We are asking the experts we know to help us decide.  If we decide to tear down, it will mean extra time to remove and ship the engine as well as adding an extra $8K t o $10K to the cost for the insurance company. 

After one SCUBA equipment failure 600' into a cave, one high speed motorcycle wreck, one low speed head-on motorcycle crash, one plane crash, and being shot once, I tend to err on the side of caution these days. I guess I do/have done too many things in my life which could kill me even if everything was working well to not do a tear down in this case.

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24 minutes ago, jaylw314 said:

AFAIK, the insurance typically covers the full tear down after something like this, right?

They normally do, since the engine manufacturer states a tear down should be done if there is any prop damage - not in those exact words. But that's reason #1 IMO, insurance is not going to argue it so why should we take the chance. But recall the recent damage that happened to Don Kaye's Mooney when the gear was retracted in the shop allowing the engine to come down very slowly  (it was no longer on jacks) - didn't matter since it damaged the prop it could damage the engine - the only discussion was that Don wanted a new factory engine versus a tear down, since his engine was still very new and the shop caused the damage.

Although insurance won't cover the full propeller cost, they usually pro-rate its value based on time since overhaul or new and charge you betterment on the time used. So it depends on the age/hours on the prop what if anything you get. But that's a cost the owner swallows regardless and insurance usually covers some of the prop cost. Insurance does cover the full inspection and re-assembly of the engine, but parts would be limited to parts damaged by the prop strike - which could include the crank. Owner is welcome to turn the IRAN into a major overhaul at the cost of the additional parts alone - which is good deal for an older engine. Here is where an owner could really make out just doing the inspection. Lets say the crank has already had it last grind done at last overhaul, meaning next overhaul is going to require a new crank no matter what. If the crank is slightest out that would warrant another grind, the insurance typically picks up the cost of that new crank - potentially saving an owner a bundle down the road if they still own it on the next overhaul.   

Now if the owner is sure they'll run the engine to TBO, it probably doesn't matter in the long run if they skip the teardown, except for betting incorrectly on inspection results. Although the chances of real damage should minimal,  not doing the tear down is going to have most future buyers question the value of the engine if a tear down inspection is not done and they learn about what happened.  Which gives us reason #2 - resale appeal and value of the engine if it does get sold in the near future. Plus everybody sleeps good at night not betting on a missed inspection to verify; that could prove priceless.

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2 hours ago, larryb said:

It it were my plane I would have the tear down done. Too many stories of a propeller breaking off 100 hours later.

I really don’t think that’s a danger here due to how it happened. Sounds like it was a relatively slow incident and the bent prop is more a function of weight than pressure. 

 

I’m not sure what I would do in this case, it really depends on what insurance says but I think I’d be fine either way. 

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Fortunately, the engine manufacturers have detailed what a ground strike is... this has been updated in the last decade or so...

Insurance typically pays for R&R and the engine and inspection... when a ground strike has occurred... see lycoming’s definition...

My plane had a ground strike once... somebody bumped into the prop’s blades.

Similar to the OP... you wait on pins and needles to hear what is going to get fixed and who pays how much...

The good...

  • inspecting everything including the engine mount...
  • R&R
  • replace the broken gear legs
  • generally put everything back correctly, no betterment... (upgrades)

The bad...

  • If the engine is near TBO, you might consider going the OH route...
  • There will be some extra cost for this...

The so so...

  • The insurance co may pro-rate some costs...
  • If you used 1500 out of 2000 hours of engine time, the loss was only 1/4 of an OH’d engine...
  • If you decide to OH and get a top prop... you can probably negotiate applying the costs of ‘the good’ towards your upgrade list.

 

Good luck with your insurance company. My issues were taken care of pretty quickly... the worst part was getting a new prop...

An engine can be OH’d rather quickly, or factory reman’d in a couple of weeks.... a prop can take months...

So focus on the long lead items if going this way...

If you have questions about your prop... we have @Cody Stallings who has been extra helpful for these kind of things...

PP thoughts only, not an insurance guy...

Best regards,

-a-

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16 hours ago, TTaylor said:

This truss is not the one that can be hurt by turning the nose wheel too far.  It is attached to that one and sits just behind it.  Two of the propeller tips were slightly damaged when they hit the ground and both blades slightly bent back.  The prop is going in for a full overhaul. The gear doors will also need to be replaced. We must comply with the prop-stike AD even thought the engine was not running.  We are still evaluating if we will need/want to do a full engine tear-down.    We are consulting with our mechanic, the engine shop, and the partners about the tear down. 

My experience is the AD will require a TDI tear down inspection of the engine even though the engine was not running, if the prop needs overhaul or replace, engine needs TDI.  Then per Lycoming SB if it has been more than 10 years since overhaul the engine should be overhauled.  Lycoming certified shops will not do the TDI unless it complies with the SB.  I don't know why Lycoming is so much more "sensitive" to minor strikes than Continental.  It's almost as bad as, "if the prop strikes more than three raindrops per revolution it must be inspected".  Someone's making $ off another's misfortune, but I guess there's a lot of liability at stake too.

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15 hours ago, Oldguy said:

After one SCUBA equipment failure 600' into a cave, one high speed motorcycle wreck, one low speed head-on motorcycle crash, one plane crash, and being shot once, I tend to err on the side of caution these days. I guess I do/have done too many things in my life which could kill me even if everything was working well to not do a tear down in this case.

You just need to stay home and watch more TV.  Dang.

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