Hangar Talkby Guest Editor – Paul Giehart | January 15, 2021

Aircraft Mechanic on a creeper dolly repairing airplane
Aircraft Mechanic on a creeper dolly repairing airplane

Former FAA Inspector Paul Giehart asks Aircraft Pilots hard questions about the Aircraft Maintenance Manual and how it pertains to FAR Part 43.13

While in the Allegheny Flight Standards Office I was contacted by a local flight club and asked to put on a short presentation and since it was on my way home, I accepted. My talk would be on preventive maintenance.

The meeting was in their hangar with around 20 pilots and several future hopefuls present. While I introduced myself, I passed a clipboard around for their names. I retrieved the clipboard and started.

I asked the following questions:

How many here have changed an airplane tire? All the pilots raised their hand smiling.

How many used a maintenance manual? About a third raised their hand grinning.

How many ensured the manual was current? Woops, two that owned new aircraft raised a hand with a broad grin.

How many assembling the wheel halves used a torque wrench? About half raised their hand much relieved.

Now for the kill question.

How many ensured the torque wrench was calibrated? Silence and gloom fell over the crowd. Not one hand went up.

Well, I said, “it appears everyone who originally raised their hand is in violated the FAR Part 43.13 regulations and I now have each of your names”. Everyone was looking at me like, “who was the idiot who invited this guy here.” No one was smiling. The room was silent waiting on my next move.

OK, I said, “I am letting everyone off the hook, this time.” Breathing returned to normal. Let us go over the procedure. Disclaimer: below is a standard procedure on light aircraft. Some aircraft may vary so check the maintenance manual for the specific aircraft.

We will take it from where all is disassembled, cleaned, inspected and we are ready to install the wheel. When the wheel halves go together, and nuts are snugged on the bolts, we need to use the current manufacturers maintenance manual to find the correct torque for the bolt size. We do not know if the torque wrench is accurate unless it is calibrated.

Now we have the bearings cleaned and lubricated, the wheel and retainer washer slipped on the axle, and the large castellated nut screwed up to contact wheel. Now, how do we know if the axle nut must be torqued or simply snugged up with zero play and tightened to the next available cotter pin hole? How do we know which process applies?

About half the pilots faintly said, “maintenance manual”. I reached into my briefcase and came out with a handful of mini snickers bars and threw one each responder. OK, now the cotter pin is locked in place and the brake pad plate is installed with the 2 bolts. I will expound on these bolts later. So, how do we know how much torque? “maintenance manual” came the voices even louder. More candy bars thrown into the group. How do we know the torque is accurate? “Calibrated torque wrench” almost all replied. The rest on my candies were thrown out.

Now, how many here know the correct way to change a tire? All hands went up.

I related the story of an aircraft accident I investigated where a Lake Amphibian landed and swerved off the side of the runway and into 3 parked aircraft. The pilot was unhurt. The cause of the accident was due to a simple tire change. The brake pad plate bolts were worn and overtightened to the point the threads were partially stripped, probably by multiple installations with no inspections. Upon landing with hard application brakes, the left brake bolt threads did not hold, and braking action was lost causing the swerve and subsequent crash.

I left there with everyone learning the proper way to change a tire and that is by using a current manufacturers maintenance manual and a calibrated torque wrench. And I was out of candy.

FAR Part 43.13. Performance Rules (General)

(a) Each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer’s maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, and practices acceptable to the Administrator, except as noted in Sec. 43.16. He shall use the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices. If special equipment or test apparatus is recommended by the manufacturer involved, he must use that equipment or apparatus or its equivalent acceptable to the Administrator.

Need Help with FAR / Certification / Maintenance questions?


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