December 8, 2016

The fix is only as good as the write-up


The fix is only as good as the write-up


If you fly in an organization with a fleet of aircraft its likely that you have a process for writing up squawks on them when something goes wrong.

Flying clubs, partnerships, flying schools, and commercial organizations alike find it not only convenient but effective to have some sort of system for recording aircraft squawks so that maintenance and the next pilot(s) are aware of the problem.

The squawks are read by each pilot (ideally) prior to flight as part of the preflight preparation. A mental note of recent problems that have been repaired and an assessment of deferred squawks are made to determine if the aircraft is sufficiently airworthy for the intended mission.

Sometimes the words “could not duplicate” are written as the mechanics’ response to problems that are either transient in nature, were simply imagined by the pilot, or so poorly written-up that the mechanic really had no idea what they should be troubleshooting.

Imagined problems do occur, but rarely, and are usually the result of the pilot hearing or seeing something they think they’ve never heard nor seen before. Many times these “problems” are a normal part of everyday operation.

Navigation radio anomalies are frequently written-up like this as a result of pilots unaware of ground facility anomalies that affect instrumentation. For example, tall corn crops off the end of the runway have been known to play havoc with the stability of the VOR signal at my home airport. That particular problem could easily be confused with a bad CDI indicator; a problem that the avionics technician will not be able to duplicate in the shop.

In the grand scheme of things, the real problem are poorly written squawks that tell the mechanic virtually nothing about the nature of the problem, nor gives them any idea where to begin troubleshooting.

We’ve all heard of some of the classic examples like, “Squeak in cockpit” to which the mechanic writes “Cat installed.” Or how about this one, “Number three engine missing:” mechanic corrective action, “Engine found on right wing after brief search.”

Regardless of the veracity of these two examples, these types of write-ups are far from adequate and usually result in a less than adequate solution from maintenance. Many times the mechanic tasked with figuring out what is wrong cannot not properly duplicate the circumstances in order to see or hear what the pilot has written-up.

In other cases, the pilot fails to provide the exact circumstances under which the problem occurred. This is especially important with engine and avionics problems since there are so many possible reasons why they could occur.

So how should a pilot write-up a problem so that the mechanic has half-a-chance of finding a solution?

First, simply indicate the part(s) that you believe are malfunctioning. Second, indicate how they are malfunctioning. Use your senses for this part. Does it smell? If so, what does it smell like? Did you see something odd happen? Describe it so a blind person could visualize it. Did you feel something? Try to describe the sensation, and do so with an explanation with which the mechanic might have some familiarity.

For example, saying that the “Nose gear doors moan like a constipated rhinoceros” may not mean much if the mechanic has no applicable experience with rhinoceroses.

Third, describe the circumstances under which the problem occurred: phase of flight, on the ground or in the air, power settings if having engine problems, altitude and distance from NAVAIDs when experiencing radio problems, etc.

If the problem was radio related, always inform the mechanic of anything you tried to troubleshoot the problem yourself. Also report any comments made by ATC on radio or transponder problems. Believe it or not, several squawks of the same nature in a short period of time, but on different aircraft, led our avionics technician to suspect a problem with ATC equipment. He was right!

Had our people not properly written up those squawks, ATC might have been unaware of their own radio problems for some time.

Sometimes, the pilot can’t give enough information about a problem to be of help to the mechanic. Engine problems are perhaps one of the most serious problems mechanics deal with, and they may also be one of the hardest for pilots to write-up due to the myriad of things that could actually be wrong.

We once grounded our family airplane for severe engine roughness and vibration just prior to final descent and landing at Moline, Illinois. The mechanics diligently checked the engine and performed a run-up, finding no problems other than some fouled spark plugs.

My father and brother proceeded to test fly the aircraft only to experience the problems again shortly after takeoff. They made a quick return to land and took it back to the shop. This time, the mechanics performed a borescope on the engine and found a cylinder with excessive oil in it. Prognosis: sticking exhaust valve. A new valve and some cylinder reworking and we were set to go.

This example is a case where there is little evidence of the cause of the problem, other than the sensation. RPM drop was not significant, likely due to it being a six-cylinder engine. The mechanics probably attacked the problem starting with the most likely sources, like spark plugs, magnetos, etc. Like doctors, mechanics, when dealing with unclear problems, will not automatically assume the rarer problem right from the start.

Under circumstances such as these, the more information you can provide, the better.

Many problems have three or four symptoms that are the same but an additional one that distinguishes between them. Having that last symptoms in your write-up could be the difference between a solution and “ops chk ok, could not duplicate.”

Writing up an aircraft squawk is something of an art. And so the pilot must be articulate enough to get across the true nature of what went wrong so the mechanic has the right cues to proceed with effective troubleshooting.

If you have difficulty putting the experience into words, the best alternative is to seek out a mechanic, or an experienced pilot at the very least, and explain your problem to him or her. For many problems, I follow up the write-up with a call to the maintenance shop when I think that they may have trouble understanding what I was experiencing.

In doing so, you also show the maintenance personnel that you are concerned about the problem and add some ownership to the solution that might not exist from a simple impersonal write-up.

Remember as well that not all mechanics are pilots, so they may not understand a squawk written in pilotese. Get your point across in plain English, but keep it short and simple and you’re more likely to see a real corrective action.

This month’s Pilot Primer is written by Donald Anders Talleur, an Assistant Chief Flight Instructor at the University of Illinois, Institute of Aviation. He holds a joint appointment with the Professional Pilot Division and Human Factors Division. He has been flying since 1984 and in addition to flight instructing since 1990, has worked on numerous research contracts for the FAA, Air Force, Navy, NASA, and Army. He has authored or co-authored over 180 aviation related papers and articles and has an M.S. degree in Engineering Psychology, specializing in Aviation Human Factors.