Preflight Procedures from a Maintenance Perspective

Preflight Procedures from a Maintenance Perspective

For many years I maintained a B200 owned by a family business that had used the same pilot for years. He had flown for the airlines and was a decent guy, but every time he picked up the King Air after maintenance, he pulled the door shut, started the engines and took off without even checking the oil!

That boggled my mind. I’ve seen a lot of preflight routines, but this was no preflight at all. Some of my guys thought I should take it as a compliment because the pilot had so much faith in the work we were putting out, but I’d rather have my work questioned and verified by a thorough preflight inspection. Needless to say, when this King Air went out the door, everyone in the shop gave it an extra walkaround before “Speedy Gonzalez” came to pick it up.

If Possible, Make a Mid-maintenance Visit

Most shops don’t allow customers in the hangar because of insurance reasons, but if you have never seen your King Air in the middle of a Phase inspection, you need to. Have the shop foreman give you a tour, just don’t be surprised by what you see, even if it looks like total mayhem. Panels are open everywhere, the engine cowls are off and wing lockers, if you have them, are removed. Much of the interior is sitting on the hangar floor and the floorboards are pulled up to expose the guts (electrical, plumbing and ducting). A control surface may be off – a flap, most likely, so the Teflon washers can be accessed for replacement.

Airplanes are 15 pounds of stuff crammed into an oddly-shaped five-pound bag and getting to it is time-consuming and nonergonomic. The skinniest mechanic gets stuffed into the hellhole where they might have to remove ducting and avionics boxes just to carry out the 12-month check on your ELT. He or she then moves on to a dozen other tasks to be performed in there.

Obviously, you are not going to re-inspect the airplane, but think about what you’ve observed as you do your post-maintenance preflight. You’re not doubting your shop; rather, you’re confirming their execution of an extremely complex job. And if you find something amiss, good shops will rush to remedy the situation. That missed item will become a learning session for all involved, not to be repeated.

Cockpit Out of Order

After maintenance, it is vital that you allow ample time to restore your “switchology” to your liking. Check everything; assume nothing. You have no idea how many mechanics and avionics guys have been in and out of your cockpit. Switches were flipped, breakers were pulled, levers were moved. The friction locks were loosened to check engine cables for binding.

Every pilot has their preferred “switchology.” When I had my shop, I made every effort to return the cockpit to the configuration present at drop off. With repeat customers, I learned their habits and preferences. However, in my post-maintenance debrief I always asked every pilot, every time, to check and restore all cockpit preferences.

The oxygen mic switch is a great example – when is the last time you touched that? Most likely it was in a simulator during loss of pressurization. But what if, during maintenance, an inexperienced mechanic puts all the switches in the “off” (down) position because it seemed like the right thing to do? He has no clue he just turned the O2 mike on, cutting out the regular mike in the process. Now the pilot arrives to take delivery of the aircraft; he’s in a rush to leave and has already taxied out before he realizes his mike is in-op. So, he taxis back in, shuts the engines down and barks at the shop because now he is delayed and frustrated.

This can happen in reverse also: Some pilots choose to leave systems in the “on” position all the time so they don’t have to remember to turn them on each time they fly. I’ve seen this with windshield heat, pitot heat and the vent blower, among others. When the aircraft goes in the shop and external power is applied, these systems come on. An unsuspecting mechanic touches the pitot tube and gets his fingerprints burned off.

The preflight procedure on a King Air, as specified in your POH, is a long and involved routine. Many are compelled to develop shortcuts. But if they are the only one that flies that airplane and assume the cockpit is the way they left it last, then they are bound to encounter unwelcome surprises when they get their aircraft out of maintenance … unless they check everything carefully.


Back in my days at BeechWest Van Nuys, there was a very sharp owner-operator with a 200. This guy was totally “by-the-book.” One day he was preflighting out on the ramp. He had an aft cowl open when line service paged him for a phone call. He left what he was doing, went inside to take the call, then came back out and continued his preflight. On takeoff that rear cowl ripped off as soon as he rotated. That’s when he realized he had forgotten to latch the cowl properly before taking that call, and afterward he failed to backtrack over what he had been doing when he was paged.

A few years ago, an owner-operator was pre-flighting his E90 when the fuel truck operator came by to clarify his fuel request. He was on a step ladder checking his oil at the time, so he got down to talk to the fuel truck operator then finished his preflight. He loaded his passengers and took off for a weekend retreat only to lose oil pressure on one side a short while later. After some very tense moments, he got on the ground safely and found the oil dipstick on that side exactly where he laid it when the fuel truck came by. This shocked him. He was absolutely certain he had replaced that dipstick.

My late father-in-law was the epitome of a thorough and deliberate preflighter. My wife remembers many hours of cooling her heels in an FBO while her dad did his preflight routine. He kept laminated checklists handy and read each item out loud as he performed the task. When she was old enough, he had her read the item out loud and he repeated it back to her as he checked it. But despite his best efforts, after 50 years of flying he left an oil cap latch open and lost oil pressure right after takeoff. Fortunately, he circled back around and landed safely, but he was embarrassed beyond imagination. Chances are, he was distracted when he was checking the oil on that side … I’ll bet his cellphone had went off!

Cellphones – a Distraction on Steroids

Although cellphones have revolutionized our lives in many ways, these devilish devices have their downside. Distracted driving is just the tip of the iceberg. In the workplace – aircraft maintenance hangars, in particular – cellphones are a menace to safety.

One item on a phase checklist can require many small tasks in succession. When a cellphone goes off it grabs attention away from the job at hand; it destroys focus.

The problem worsened when text messaging became common. A short conversation becomes five or six “dings” and each one is an interruption. In my shop I had a zero-tolerance policy on cellphone usage that required mechanics to keep their phones turned off and stowed in their toolbox, not in their pocket on “vibrate.” I fired two perfectly good A&Ps for violation of this policy.

In one case we were changing the engine mounts on a B200 before installing new engines. The metal portion of the mount assembly attaches to the engine case with four bolts. Two rubber blocks (isolators) “sandwich” around the mount. A large bolt runs through the center of this “isolator sandwich” to the engine truss. There is a sequence of tasks to install these; the four bolts going to the engine case must be safety-wired before the isolators go on. Otherwise, it is next to impossible to “safety” them later. On a 200, with four engine mounts per side, there are 16 bolts to “safety” per engine.

The mechanic assigned to the left engine was great when she followed my directions. But on this day, she was going back and forth to her tool box way more than necessary. When I checked her progress, I found all the rubber blocks in place but the bolts weren’t safety-wired. I asked, “Aren’t you going to safety-wire these?” She said, “Well, I got distracted.” And then I heard the soft “ding” of her phone, in her pocket. She went back to her toolbox where she surreptitiously texted while appearing to search for her safety-wire pliers.

Aircraft maintenance is complicated enough without cellphone distractions. Many times I have woken up in the middle of the night, unable to remember if I “safetied” everything properly. I have even got out of bed, got dressed and drove to the airport at 2 a.m. to double-check myself to put my mind at rest.

I know of larger shops where the managers use text messaging to communicate with mechanics in the hangar. I vehemently disagree with this practice. First, the mechanics don’t need more distractions and second, the use of cell phones on the job should be discouraged, not encouraged. Thirdly, the desk drivers might benefit from some firsthand hangar observation to keep their finger on the pulse of things.

In my opinion, you don’t need your own phone going off during your preflight routine any more than you need cell phones distracting mechanics while they work on your aircraft. You could just as easily be sidetracked like the pilots I mentioned above. It could be the line guy, the fuel guy or an impatient passenger. Why add to the chaos? Your phone can be turned off.

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