Torque figures are for clean dry threads. Locking compound is sort of a lubricant, of unknown value from compound to compound. No locking compound in aluminum. Eventually the threads come out glued to the bolt. Bolts in iron or steel threads are OK for locking. Studs in aluminum that in normal service are permanent can be locktited. Bolts that you expect to remove from time to time in aluminum will eventually remove the threads, and a repair will be required. Better to wire the bolt and never have the problem. Studs only need to be snug in their holes. In steel or iron, Loctite is fine. (They call the red stuff stud and bearing mount) The blue stuff for aluminum. Any aircraft bolt or screw can be ordered with a wire feature. It part of its part number. The wire hole is not a factor in the fasteners strength rating. Nuts on studs need no locking compound. The stud will come out on the nut. Wire the nut instead.
I did a study once to determin if Uncle Sam was spending too much for hose clamps used on aircraft.
The troops see the Chinese hose clamp on a nail at the parts store for 45 cents, and an "Ideal" hose clamp from the bench stock (it was years ago) and that one is $2.60. So they complain and submit a savings report.
The government actually buys every kind of worm clamp ever heard of and in their thousands. So the helicopter mechanic who has a piece of equipment that uses a non aircraft clamp can get one with the right NSN. But is not authorized to install it unless the TM or TO calls out that particular clamp by and NSN.
The clamp on the nail at the parts store has only a screw driver slot to tighten it. No wire hole. It would probably work OK, and it probably wouldn't come loose between 100 hour checks. Probably........most unlikely........seldom if ever..........not very often at all..................
The clamp in the TO or TM has a pedigree. The manufacturer has electron beam etched a lot number on every clamp made that day. Two clamps from every lot are retained by the manufacturer forever. It is 316 stainless not 304 stainless. It has a screw driver slot and a hex head. It is drilled for wire. The wire holes are chamfered. At random during production a number of clamps will be removed from the packaging line and tested to 150% of rated capacity. So why do the very best aircraft hose clamps ever made, have a lock wire feature? Because they all must be wired. In the event you forgot, and this bird is not chained down in the runup area at 9:00 AM exercising her new engines because you are still here wiring clamps you should have wired yesterday, you my E-3 friend will be an E-2 in Afganistan wiring hose clamps on helicopters 8 hours each day at 130 degrees, and sorting sheep shit an extra 2 hours each day until your enlistment ends. Wire the clamps.
Lynn E. Hanover
Wow! The differences in opinions is so varied when it comes to the subject of safety wire. From absolutely nothing to almost everything, and whatever may fall between. Ed, you have your oil pan drain plug and your oil filter wired with very little else. John you mentioned that your oil pan bolts are wired. Are these all of the small 6mm bolts? If so; how did you wire them? Did you drill them, are they weaker because of this as someone has mentioned? Also John; What type of mount are you using? Is it the bed mount that relies on the 6mm bolts? You would not want to weaken any of these bolts however you wouldn't want any of these bolts to come out. Al, you mention that you don't have anything safety wired and haven't experienced anything important coming lose in a car. I have and it was very important. It was a tube and o-ring related to the coolant system that was held into the block by one bolt. Needless to say the one bolt backed out, I lost coolant over heated and I
pulled over to the side of the road. I cannot pull over in a plane. It would be nice if we didn't have to wire anything, however we must decide what is critical. Bill, I think that your knowledge as a racer is priceless. We could all benefit from you knowledge and find out what falls off of motors that we really don't want to fall off. It would appear that oil drains and coolant drains are the most important in racing. Not only does it protect your engine from complete failure from oil loss or coolant loss, but it also protects other racers on the track as these fluids if spilled onto the track become very slippery. And once again Ed, you mention that drilling bolts could weaken them, and I agree. So the question is; When is a bolt or nut to small to drill? Bill, I also agree with you when you say that "most bolts don't need safety wire if you remember to tighten them". However what I find interesting is that no one has mentioned or suggested the use of thread lock along
with proper torquing. And as far as the tension bolts go from what I understand is that Tracy Crook does not recommend safety wire on these bolts. He does however recommend the use of rtv sealant on these bolts. What about sealant and thread lock? Thanks everyone.
Keith
RV-7A
13-B