Use the Murphy Never Sleeps type of assuming.

 

If you don't need it, don't safety it. It will eventually fall off. Safety includes bobby pins and cotter pins. Murphy slips in at night and backs off every fastener 1/4 turn. Murphy never sleeps.

 

An old saw used to be bolt heads up and forward. Why is that? Because the nut will eventually fall off of every bolt you own. When it does, it will stay in place if the head is up and it just hangs in the hole or the head is forward and the wind will hold it in place.

 

Shear bolts do not get torqued into a working range. they have just a short thread run. They use very short nuts. They have a nut on them to keep them in place, not to develop a tension load. They need a bobby pin or wire to keep the nut in place. Tension bolts have more threads and use taller nuts. They get torqued into a working range. Their nuts may not have a locking feature at all. They must be safety wired. 

 

The rotary installations have less vibration than piston engines. There is less a problem with loose fasteners.

There will be no problem with loose fasteners if they are all safety wired. Its good practice. It looks sexy.

Very few planes have been lost to excess safety wire. Imagine each piece of the pie, if it came loose. Would it rub on an oil line? could it wedge the throttle closed? could it punch a hole in the radiator? Are the hose ends/ "B" nuts on your oil lines safetied? They should be. You can buy a block full of bolt and nut holes to use for drilling wire holes where none exsist.

 

Remember, Murphy Never Sleeps.

 

Lynn E. Hanover

 

 

 

Hello everyone,

I know that the subject of safety wire has been discussed many times before,  however searching the archives can at times be very difficult and actually finding the answer you want is like winning the lottery (it never happens).  What I would like to know is what most are considering an absolute must to be safety wired.  What the FAA requires and what is not so important but some are doing anyway.  I feel that the subject of safety can never be discussed enough.  I would like everyone that has an opinion on safety wire and what must be safety wired to weigh in on this subject.  I plan to save some if not all of your answers for future reference.  Maybe we can make a list of what must be safety wired.

Thanks
Keith
RV-7A
13-B