replace main landing gear bolts every 500 hr?

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kayakalex

New member
My mechanic was going thru the Inspection Report in the service manual and tasked me with researching item G2: Replace main landing gear thru bolts and U-bolts at 500 hr intervals.

I've been thru the logs, and in almost 2500 hr TT, I can't find any indication that this has ever been done. It seems unlikely that all of the dozens of mechanics who've been thru this plane have simply missed this item. This is only my third annual, and since I relocated last year, I have a new mechanic and this is his first Citabria. What should we do?

At the risk of hijacking my thread before it even posts :lol: I have to comment on the log entries I've been reading. They range from terse:
"I have inspected and found airworthy" <signature>
To vague:
"...in accordance with Citabria service manual..." (with no indication of what parts may have been replaced :x )
To whimsical:
"8-24-80 25 hr Wash airplane. Tach 750.0"

To sum up, I know my plane was washed no less than seven times in its first 1000 hours, but can't be sure the gear bolts were ever checked.

Thanks for listening. Any advice appreciated.

-Alex
 
Call Mandy at ACA and get your self some new hardware and change out the old stuff.
Its not uncommon for the IA to not have a service manual. And since its not an AD, many know nothing about the recommendation to change the bolts.
 
I sifted thru receipts and found what I was looking for. The previous owner replaced the gear legs and bolts 540 hours ago, and re-torqued the bolts 100 hr later. No action since then, so I'm due for a torque check at least. The bolt set cost the last guy about $280, and I'd guess it's a 2-hour job. Would I be foolish to defer replacement for later? What are other people doing? -Alex
 
Well Alex, it looks like you have answered your own question here. If the bolts are to be replaced every 500 hours and yours were last replaced 540 hours ago, it seems logical that yours are overdue for replacement, not just a torque job.

I'm not trying to be a smart a_s here, I just think that if there is a 'requirement' to do something...even if it is NOT an AD...then there must be a pretty good reason for requiring it, and therefore it ought to be done at the time limit that was set.

Helicopters have many 'life limited' parts that HAVE to be replaced at a set number of hours, regardless of how good the part may look. If it reaches the hour limit it's gone...no questions asked.

Just consider your landing gear bolts to be the same type of thing. The manufacturer has set a 'life limit' of 500 hours on those bolts, so now it's time to replace them.

I know it gets expensive buying all these replacement parts, but gear bolts are cheaper than a complete rebuild of your bird if those bolts fatigue and break and your plane cartwheels out through the rutabagas!

My 2 cents worth.........
 
Yeah, I was looking at those bolts thinking about what would happen if one popped during one of my less-than-graceful returns to earth. Rutabagas would be a blessing compared to our more common Douglas fir, etc :oops: I've already rebuilt the wings once...

More info: Around 1900 tach time, the original U-bolts were replaced with the bar & bolt setup. The original hex bolt (MS2005-32) was replaced with an Allen head bolt (MS2007-32). It seems the bends in the original U-bolts were good places for cracks to develop, so the U-bolt was replaced with a very stout steel bar with bolt holes in each end. I imagine lots of Citabrias have been retrofitted with this.

Does the new hardware have a new maintenance schedule?

Thanks again. -Alex
 
Hi Alex,
The bolts your inspection checklist is talking about replacing are the "through bolts". These two bolts are located on the inner part of the gear. I was just like you and could not find any reference in the logs to the bolts being replaced. I replaced the inner through bolts first, had to cut two small holes in the bottom fabric to replace these. I then replaced the u-bolt type outer bolts with the new bolt and bar setup. You might as well go ahead and replace them just for the peace of mind it will give you. The cost is not that bad, even though Mandy said they were pricey, I told her not to worry, If one broke that would be where the price would come in.


Woodie
N29763
 
The bar style U-bolts that we use now have no instructions outside of torque. They are a gross over kill and don't really need any.

The Thru-bolts however actually take a lion share of the load. They are much less expensive and need to be replaced every 500. Those who have lived in the rough stuff know what that bolt looks like after abuse....hehe.
 
Thanks, Woodie and Jerry! That makes a lot of sense. I ordered the inboard bolts this morning. Mandy is also sending a copy of the updated inspection report. -Alex
 
Years ago, on a 7ECA I had the inner bolt break.....luckily it was on the right side and the plane came down on the step. Bent one of the lift struts, got the prop.........and since it was on the step side, it just barely scrapped the right wing tip......no damage. Very lucky......also it was on a grass strip. I think about $200 and we were flying again........of course this was about 1969 or so. When we looked at the bolt, you could see where it was cracked half way thru for some time........so, in my opinion, for what it's worth, I changed the bolts on a regular basis.
Brian
 
Hi Woody, (or anyone who has done it)

Were you able to change those through bolts without hoisting the airplane off the gear?

Thanks!

Bill
 
I had my thru-bolts replaced dring the 2007 annual inspection after reading the posts above from Jerry. I believe the machanic said he just attached an engine hoist to the engine and lifted just enough to take the weight off both gear legs.

Paul
 
We also have a little adapter for jacking up one side at the strut/fuselage attach.
It basically hooks to the welded shear plate there.
 
Hi Jerry,

I just had a look at my landing gear bolts. I have the new MS Allen Head hardware in there. When I read my service manual, it says the AN type bolts need to be replaced at/before 500 hours, then recommends the MS type.

Does the MS type still have the 500hr hour change recommendation?

Thanks!

Bill
 
I was thinking of replacing mine (u-bolt assembly) at the next annual due next summer (7GCBC)...so how much are those again?

Bruno
 
I just ordered a set for my 8KCAB. There are 6 total at a cost of $33.00 / pc plus $33.00/ pc for the nuts. They are not AN or MS, but are BAC which is Boing Aircraft, which must explain the cost.
 
Jerry -
Thru Bolts:
Are there two ? And what is the list price for 1 (or 2) from ACA/Rochester pls.
Thanks -
Jim Robins
N87VF
 
There is one for each gear leg.
They run $33.19 each and the nuts are another $33 each. Nuts are optional, dependin on how yours look.
 
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