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Engine Mounts

MWH265

Well Known Member
Working with my mechanic I had to pull the bottom engine mount bolts to correct a washer configurement. I have Barry mounts on an IO-360 angle valve engine. The bolts on the engine mount have castle nuts with cotter pins. Would it be ok to replace the castle nuts with locknuts to avoid the task of lining up and properly installing the cotter pins in a very difficult location?

Thanks,
Mike
 
Aligning holes on bolts

Use a sharpie on the end of the bolt so you can tighten the castle nut to the correct position
 
Out of curiosity, just trying to learn here, why would I need to change out the bolts? There doesn't appear to be anything wrong with the bolts, I would just be changing the nuts for convenience. I always use all metal lock nuts in the engine compartment when lock nuts are needed.

Thanks,
Mike
 
I thought this would be an easy look up in AC43.13 for an explanation and procedure standard, if it's written there, I couldn't see it... I do know it is what is taught in the various courses & seminars I've attended and harped on by old time mechanic buddies I know. It is the standard that must be complied with if you want to pass Final Inspections in Canada, I would assume the same thing for the US.

I did find a statement in EA-282-0 Standard Aviation Maintenance Handbook section VII, Aircraft Hardware
"If a self-locking nut is to be used, the shank should be undrilled. This is designated by a letter A following the dash number, Example AN4-6A"

Still no explanation why... other than maybe - you probably loose some structural integrity of the nut/bolt contact area if a portion of that area is a hole.
 
Working with my mechanic I had to pull the bottom engine mount bolts to correct a washer configurement. I have Barry mounts on an IO-360 angle valve engine. The bolts on the engine mount have castle nuts with cotter pins. Would it be ok to replace the castle nuts with locknuts to avoid the task of lining up and properly installing the cotter pins in a very difficult location?

Thanks,
Mike

The cotter pin is no problem. Like mentioned, mark the bolt end with the location of the hole. Torque the bolt and line up the hole. Insert a cotter pin and turn the bolt till the cotter pin can be bent into position.
 
I thought this would be an easy look up in AC43.13 for an explanation and procedure standard, if it's written there, I couldn't see it... I do know it is what is taught in the various courses & seminars I've attended and harped on by old time mechanic buddies I know. It is the standard that must be complied with if you want to pass Final Inspections in Canada, I would assume the same thing for the US.

I did find a statement in EA-282-0 Standard Aviation Maintenance Handbook section VII, Aircraft Hardware
"If a self-locking nut is to be used, the shank should be undrilled. This is designated by a letter A following the dash number, Example AN4-6A"

Still no explanation why... other than maybe - you probably loose some structural integrity of the nut/bolt contact area if a portion of that area is a hole.

notice it says should, not must. the biggest reason if when using fiber locknuts. a burr in the hole can cut the fiber insert and effect its locking ability. I have never heard of the requirement to change the bolts here in the us.
 
Torque on engine bolts

What should you torque the engine bolts. I’ve asked a couple of people and they said snug but I find that hard to believe that there isn’t a torque value
Thanks
Daren
 
Torque value - look at the Lycoming overhaul manual, or Superior's torque table -- unless Van's calls for something different.
'Snug' don't cut it.
 
What should you torque the engine bolts. I’ve asked a couple of people and they said snug but I find that hard to believe that there isn’t a torque value
Thanks
Daren

According to the Van's construction manual, use the torque value for an AN7 bolt, which is listed as 37.5 to 41.7 foot pounds.
 
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