You don’t know what you don’t know
By Joe Escobar
Training. In aviation, it is a fact of life. From company training to OEM specialized training and even FAA training, there are many resources available for A&Ps wishing to further their knowledge. Yet there are a few mechanics who don’t see any value in training and offer comments such as "I have worked on aircraft for years, I don’t need to be trained" or "I know what I’m doing — I don’t have time for all that feel-good, mumbo jumbo."
To emphasize the importance of training, Rodger Holmstrom, the Airworthiness Safety Program Manager for the FAA’s Birmingham, Alabama FSDO, has developed a presentation called the "Eye Opener." It has fostered an increased commitment to training by mechanics who have attended the seminar, as well as increased participation in the AMT Awards Program. I was invited to attend his presentation earlier this year, and was truly impressed. The response from those in attendance was overwhelming. Many of the mechanics who were there, thanked him for opening their eyes to the importance of training. The following is based on his presentation.
Proud to be a mechanic
The year was 1903. The Wright brothers completed the first powered flight at Kitty Hawk. The Wright brothers had a great idea and Charles Taylor made it happen. He designed, built, installed, rigged, and tuned the engine that powered the Wright Flyer into history. Like mechanics today, his contribution to that eventful flight was not celebrated. He stood in the shadows of Orville and Wilbur with the proud knowledge that he made it happen.
Mechanics are taken for granted. We are the foundation of aviation. And, like the foundation of a building, we go unseen by most. Nobody walks up to a great building like the Washington Monument and says "Wow! What a great foundation!" Yet, you pull that foundation out from under it, and you’ve got a problem.
Like the foundation of a great building, mechanics are susceptible to erosion. We are susceptible to erosion by ignorance. One might be overheard saying, "I’m not ignorant — I just didn’t know." In the field of aircraft maintenance, ignorance can be lethal.
The good news is that there is an anti-ignorance program called the FAA AMT Awards Program. This program promotes participation in initial and recurrent training. The FAA recognizes eligible mechanics and their employers by issuing awards to those who receive and foster training.
So, why is the FAA so interested in initial and recurrent training? Because without it, you don’t know what you don’t know. Think about that statement for awhile. It is an interesting thought.
The following are true stories. They are not about dishonest people. They are not about crooks. They are about sincere, honest, hardworking mechanics. They had all the best intentions. But they all had one thing in common — they didn’t know what they didn’t know.
Registration certificate replacement
Replacing the registration certificate doesn’t require any special knowledge or training — right? After all, it’s just a piece of paper that is secured to the interior sidewall with a plastic cover that is held on by a few screws. It is just a simple task. What could go wrong?
While en route in normal cruise flight, the pilot reported smoke in the cockpit and requested to divert. Smoke filled the cabin, and the passengers were terrified that they were going to crash. A descent was commenced, and the aircraft landed safely at Birmingham, Alabama. Upon inspection, a charred hole was found at the Registration Certificate. The mechanic who had replaced the certificate thought that since it was just a piece of plexiglass covering a certificate, it didn’t matter what screw he used to secure it. He used slightly longer screws with points to them. What he didn’t realize was that there was high amperage wiring behind the sidewall. Over time, the screw ended up chafing a hole in the wire insulation, causing severe arcing before the slow-blow circuit protector blew. Once the arcing commenced, it caused a smoldering fire in the adjacent area. A point to note is that in some aircraft, an oxygen line runs in this same general area. Had a short like this occurred in the immediate vicinity of that oxygen line, the aircraft could have experienced a catastrophic explosion.
A Bonanza owner and another pilot were flying his newly refurbished aircraft home — a new engine, new propeller, new paint, new interior, new radios, and a new autopilot — basically a reincarnation. He was extremely proud of it.
About 1/2-mile from landing, white smoke started coming out from the instrument panel. About a 1/4-mile from landing, the smoke turned black and filled the cockpit. Flames started coming out from under the instrument panel and were burning the pilot’s legs. The pilot managed to climb over the seat into the back seat while the aircraft was on short final. The other pilot held open the door with one hand so he could get air and see, while he struggled to maintain control of the aircraft amidst the smoke and flames.
As the aircraft landed, smoke and flames were whirling around the cockpit. Immediately upon landing, the pilot veered off the runway onto the grass and evacuated the aircraft. They survived. If the fire would have occurred just minutes earlier, they wouldn’t have.
The avionics power bus lead had rubbed against the oil pressure line. On older Bonanzas, they have a tube that comes into the cockpit from the engine with oil to a bourdon tube pressure gauge. Newer Bonanzas have a transducer on the engine with wires running to the pressure gauge. The mechanic wasn’t familiar with the old method — he had only worked on the more recent models. He had secured the lead to that copper tube. The tube eventually rubbed through the insulation on the wire, causing an arc. The arcing burned a hole in the copper tube causing a 70-psi spray of oil to hit the arc and ignite.
The glider owner/pilot was well liked by everyone, especially by his mechanic. When his mechanic found a crack in the wing of the glider, he wanted to protect his friend from any possible harm. He had plenty of experience with fiberglass, so he reinforced the area that was cracking to prevent further crack migration.
The wing was designed to be flexible. The repaired area created a stress riser at the edge of the repair. This caused the wing to fail in flight, killing the pilot. The structure was made of carbon fiber, aramid fiber, Kevlar® and resin built in an autoclave. The maintenance manual stated "no structural repairs permitted." The mechanic hadn’t read that part of the manual.
Fuel line replacement
During an Annual inspection on a Bonanza, the IA found a dried-out, cracking fuel line. He started the installation on a Friday, stopped for the weekend, then finished the installation on Monday and approved the aircraft for return to service.
It was the pilot’s daughter’s birthday. As a birthday treat, he took her and her two best friends for an aircraft ride. After takeoff, the engine quit and the aircraft crashed into the rocky terrain below, killing all four.
In their investigation, the NTSB found a bee in the recently replaced fuel line. The mechanic had left it uncapped over the weekend.
The pilot was pulling the Queen Air out of chocks while his son was walking alongside the left-hand wing to ensure clearance. As the pilot applied differential power to make a left turn, the nose wheel assembly separated and shot out towards the wingtip, severing the son’s right leg from just above the knee.
A mechanic had recently worked on the nose wheel assembly. When replacing the nuts on the wheel halves, he didn’t have the ones called out in the manufacturer’s maintenance manual, so he replaced them with what he thought was a good substitute. Being a mechanic and not an engineer, he didn’t realize the nuts he substituted were designed for shear load applications, not tension loads like the wheel assembly required. The eventual failure was inevitable.
It’s all in the training
Incidents like the ones above can be avoided with proper training. The training can even be self-taught. Before starting a task, sit down and read the manual including applicable service letters, service instructions, and service bulletins. The FAA’s Mechanic’s Personal Minimums Checklist is a good tool to use to ensure the task is performed properly. Any extra training we receive can help stop the erosion by ignorance, and ensure we are never involved in an aircraft incident.