Your Most Dangerous Flight You Must Trust but Verify

Your Most Dangerous Flight You Must Trust but Verify

Over the last several years of watching King Air pilots in both their aircraft and in the simulator, it is obvious that they typically have developed their own cockpit flows and use of checklists. As Tom Clements has outlined time and time again, when you are new to flying a King Air, the checklist should be a “Do-List.” The difference between a Do-List and a checklist is the Do-List is a step-by-step guide you should complete each and every time you fly. On the other hand, a checklist is a list of items that are done as a “check” or verify list. Over time, each pilot develops their own flow patterns and use the checklists in their own way. Some read them aloud, some look and verify, some breeze through them much too quickly and others use them to block the sun from the side windows or windshield.

Tom has an article titled “Looking Isn’t Seeing” in which he discusses the phenomenon referred to as expectation bias. Many times during an instruction flight, he has pulled an engine gauge circuit breaker causing the gauge to drop to a zero reading, yet when the student reads the checklist and looks at the gauge they fail to notice the abnormality. Why is this? Because they see what they expect the gauge to read, not what their eyes are actually reading. Tom says there are two main reasons for this: (1) Going too fast and (2) A lack of judicious suspicion.

Your Most Dangerous Flight

Some would argue that every flight should be viewed as your most dangerous flight. However, from too many recent King Air accidents there seems to be an all too common theme – it just came out of maintenance.
No maintenance personnel wants to deliver an aircraft that is not airworthy and no pilot wants to feel like a test pilot on the first flight.

Most pilots are not A&Ps and most A&Ps are not pilots. How do we get each of the two disciplines to understand the other? The Phase inspections, calendar items and cycle items on a King Air maintenance schedule are very detailed and take a considerable amount of time to complete; some are very invasive to the aircraft.

Maintenance providers are liable for their work and most are very diligent about how they perform the tasks and how it is documented in the aircraft log books. They want it to be correct the first time, every time.

So why is your first flight out of maintenance your most dangerous flight?

If you stood and watched how much tedious work is required in your Phase inspections,  engine or prop overhauls and avionics upgrades and how much of the aircraft was disassembled, inspected and reassembled, it is an amazing amount of labor (as referred to in more detail in Dean Benedict’s article on page 22). To verify their work, technicians perform various checks, ground runs, and in some larger shops they have a final inspector verify the work … but all too often there is no test flight.

Maintenance technicians do everything in their power to provide a safe, airworthy aircraft. However, to perform all the tasks required for maintenance they must make significant changes to the aircraft that we, as pilots, must verify are back to “normal” prior to any flight. We all know how long it takes to complete a full run-up and that, on a daily basis, some of the items may be deemed unnecessary (fuel sumps, tire pressure, etc.). Any time an aircraft comes out of maintenance you want to trust that your shop did everything correct, but it is up to you to verify it. Remember? Trust but verify.

Look at a typical maintenance visit. After doing your best to describe any outstanding squawks and agreeing on all the items to be completed, you leave the aircraft in your shop’s hands. Depending on the maintenance to be done, the first thing is to clean out the cockpit and cabin and put everything in a box or bags for temporary storage. That includes headsets, cords, charts, pens, pencils, manuals, checklists, etc. … everything you are used to using on every flight. Then the actual maintenance begins. Flight controls are checked, trims are moved, friction locks are loosened, circuit breakers are pulled, seats are moved or even removed, switches and levers are changed and that is just in the cockpit!

After the maintenance is complete, it would be nice if all was put back just as it was found. However, expecting maintenance to put everything back the way they found it is unrealistic. This is where you and your memory come into play. You try to remember where levers were switched and if you even have all the items that were with the aircraft when you dropped it off. Your phone might be your best friend here. Take pictures of the cockpit when you drop it off, note everything that was there and make sure you have it when you begin your after-maintenance checks. I have heard stories of “unloading the box” of items and thinking you had it all only to realize there were no charts for the approach.

Or, after landing, noticing that the control locks were nowhere to be found. Of course, forgetting to bring new databases to load often presents us with an illegal IFR machine. So begin this preflight inspection as if you had never seen or flown this airplane before.

Preflight from a Pilot’s Perspective

Below are some examples of surprises told by Tom Clements that he personally experienced or has firsthand knowledge from stories told to him by colleagues and customers.

Static Air Line Drains Left Open

My company, Flight Review, Inc., owned and operated a 1972 C90 throughout the 1990s. Once I was picking it up by myself from a shop we often used after a routine Phase inspection. It was a lovely clear morning. I did a thorough exterior and interior preflight inspection and performed all of the run-up checks before takeoff. I lifted off at about 100 KIAS, pitched up to my standard +10 degrees attitude, retracted the landing gear, did a quick scan of the engine gauges, and then returned my scan to the flight instruments. What the …? My airspeed was only 80 knots! I rechecked the torque gauges to ensure I was at takeoff power and rechecked my pitch attitude both visually and with the attitude indicator – all normal. Knowing “pitch plus power equals performance,” I was sure the airspeed indicator was faulty. But dang, so was the one on the co-pilot’s side! By then, the indicators were decreasing below 60 knots. I reached over and moved the alternate air selector lever to the alternate position; nothing happened. I leveled off at 1,500 feet AGL pattern altitude, pulled power back to the middle “magic number” (500 ft-lbs for this C90), and stared in disbelief at the airspeed indicators that now were reading extremely high … since they had decreased so much that the needles were beginning to point to the numbers to the left of zero!

Suspecting the problem, I reached down to the Pressurization Control switch and moved it to the Dump position. The cabin was only about a thousand feet below the airplane with 0.5 psid differential pressure so the dumping was not at all drastic. Immediately, the airspeed indicators resumed normal operation. I announced on the Unicom frequency that I was on left downwind for landing, proceeded with a normal landing, and taxied back to the shop’s ramp. I knew what was likely wrong and, sure enough, they found the static air line drains were all open. This allowed cabin air to enter the static system since the drains are behind an access panel low on the right sidewall of the cockpit, inside the pressure vessel. The entrance of cabin air, being at a greater pressure than ambient, was what led the airspeed indicators to read low, since they sensed less of a difference between pitot and static pressure. It absolutely blew my mind that a half of a psi error could lead to a negative airspeed indication!

Once the drains were closed, the next takeoff was, of course, normal and I departed on my way. In the shop’s defense I will mention that the drain valve blade “handles” were unusual. When the metal blade was parallel with the drain line, the drain was closed. Vice versa, when the blade was perpendicular to the line, it was open. In fact, as we examined the drains we noted that someone previously had used a Sharpie to draw a picture on the back side of the access panel, showing clearly the proper open and closed orientations of the blade. The mechanic obviously did not notice that picture.

Could this mistake have been caught before takeoff? I doubt it, except by observing the airspeed indicators during a ground pressurization test. The main takeaway here is the advantage of making that first flight in day, visual, conditions. I hope I could have handled this abnormality successfully even at night or departing into a low overcast, but I am thankful that those conditions did not exist. I would encourage strongly that the first post-maintenance flight be VFR.

A 300 in Sad Shape

A customer and friend, an owner-pilot of a later model 300, was in the habit of asking me to help him perform the post-maintenance acceptance flight. I enjoy doing this and was happy to provide my assistance. First, I observed that the threshold and cabin door step lights were inoperative. The mechanic found a short in the wiring and had it fixed in a relatively short time. Doing the cockpit check I found that the Engine Anti-Ice switches were Off, although it is proper procedure in the 300 to have the ice vanes extended (Engine Anti-Ice On) for all ground operation. When questioned about that, the mechanic stated, “It is easier to reinstall the cowling with the vanes up.” That explains it, I thought. But it dawned on me later that either he never did a ground run-up after the cowls were reinstalled or else did it with the vanes up … increasing the chance for FOD. Either is unacceptable. After we reached the run-up area and performed the complete procedure, we found that neither side’s propeller autofeather system was functioning correctly. That system is a required, no-go item in all 300s. The right-hand side had no autofeather action at all, whereas the left-hand side had everything happening at the higher torque value. (At 17% torque the opposite annunciator should extinguish and actual feathering should occur near 10%, but here it was all happening together at 17%, indicating a chance of feathering both propellers at the same time!)

Needless to say, the 300 was not picked up that day, but nearly a week later.

The E90 Flamer

This is a story that happened at the old United Beechcraft facility in Wichita. Once United Beech had a horrific accident due to a King Air’s engine being started while the airplane was on jacks in the hangar! The plane came off the jacks and ran into other airplanes. What a mess! In reaction to that incident, a shop procedure was implemented requiring the ignitor circuit breakers (CB) to be pulled whenever a King Air was in the hangar.

A two-pilot crew came to pick up their E90. After a quick look-over they hit the right Start and Ignition switch to prepare to taxi and depart. As the N1 stabilized, the condition lever was advanced from Cut-Off. Without the ignitors receiving power due to the tripped CB, no light off occurred. Hmmm. “Oh wait, I know!” says the left-seater. “They usually pull the Ignitor CBs here. Check down there on the end of the pedestal.” The co-pilot did as requested and pushed the CBs back in; the linemen tell of a flame that went nearly the full length of the airplane! That resulted in engine damage, burnt deice boot and scorched paint.

In my opinion, two mistakes were made. First, a more thorough cockpit check should have caught the tripped CBs before start. Second, the pilot was obviously not in the habit of verifying the ignition annunciator illuminated while waiting for N1 to stabilize … an important habit to form.

Loose FCU Connection in a 200

Many years ago, I was asked to be PIC on a 200 that had been modified by Commuter Air Technology (CAT) into a 13-seat “Catpass” commuter configuration. High density forward-facing seats, a cargo pod, panel-mounted avionics … these were some of the changes made to convert this executive airplane into a commuter. The CAT marketing department wanted to take some photographs showing this airplane in its element – all seats filled and a professional crew up front. They even provided me with a four-stripe uniform and captain’s hat to wear! We taxied out at Scottsdale, Arizona, with the cameras running. Unbeknownst to me, the plane had not flown in some time while the modifications were being made. The preflight checks all proved to be OK so we were cleared for takeoff. Just as power was being set and we started to roll, the right engine spooled back to low idle. We idled to the next turnoff, told the tower we were aborting, and requested permission to return to the run-up pad. There, we could duplicate the problem. Power would come up fine for a bit, then abruptly go back to idle even though the power lever was still advanced. This had not happened during my earlier run-up. We taxied back to the CAT facility and aborted our photo shoot plans for that day. There, it was found that a safety wire had not been installed and this allowed the connection between the power lever and the Fuel Control Unit to slip, leading to the situation we experienced.

Could I have found this malfunction myself during the preflight? Sadly, I doubt it. Although I had opened the cowling doors to look for general condition, I don’t trust that my eyes would have found the missing safety wire. The takeaway here? Had I known before that this was the plane’s first flight after the mods, I should have refused to load it with passengers until after a crew-only test. Had the slippage not occurred until a short time later, it could have happened just at or after V1 … never an experience wished for, but especially not with 13 passengers onboard!

Other Experiences

A common incident that happens on the first post-maintenance flight is to discover that the upper, forward cowling is not secure. As airspeed increases, the cowl will start to lift. On the walkaround, be sure not only to verify that the arrows on the latches point as they should but also take the palms of both hands and give that cowling piece a really sharp blow, trying to dislodge it upward. If it comes undone, it’s time for the mechanic to adjust the latches properly.

What if the upper forward cowling does begin to lift in flight? One, slow down; two, extend the ice vanes. Both of these actions will reduce the pressure inside the cowl and decrease the chance for the piece to depart completely as you return for landing.

For all of the older King Airs that still have the “chin type” cowling with the electrothermal deice boot, realize that every time the cowling is removed the electric leads to the boot must be disconnected. Vice versa, they must be reconnected upon cowling installation. Yet it is impossible to verify the connection before takeoff, since this system is prevented from operating on the ground due to squat switch activation. So you, the “test pilot,” must turn on the lip boots separately, left and right, in flight while observing a slight increase in loadmeter readings. Only when that amperage increase is verified do you know that the boots were truly reconnected.

Do you know that in most King Airs the battery box cover can be installed backward? The air vent louvers need to be at the aft end when installed, not in front. Air cooling is not nearly as important now as it was when NiCad batteries were common. Still, let’s position the cover correctly.

If your airplane has undergone a significant avionics upgrade, it is so very important to do a flight test to verify that it is doing what it is supposed to do. Even the most capable and conscientious avionics shop cannot know for sure how an autopilot will track that new LPV glide path, for example, until it is demonstrated in flight. So many, times I have found rather mind-blowing errors in this arena. One King Air would track its new GTN750 GPS course just fine in the normal leg mode but it would always go in the exact opposite direction when in OBS mode. Another would never enter a programmed holding pattern. Instead, it would merely turn to the holding course heading and fly that until it ran out of gas!

I have seen a newly-installed GPS unit that never had the HSI’s course needle deviate from the center position! And this was far enough back in time that a flight test was required to gain IFR GPS approval … and the flight test had been signed off as satisfactory!

The Killer of Killers … Loose Friction Knobs

This is VERY important. Many pilots ensure their friction knobs are snugged up properly once and never give them further attention … which is OK. Others fiddle with the friction often, loosening it for taxiing and tightening for flight and that’s also OK. But pity the pilot who never adjusts them and then assumes that they are at the same setting when leaving the shop as they were when entering it. Folks, whenever engine rigging takes place, it is common that the friction controls will be backed off to the totally loose position. This allows the engine-end of the control to be moved freely by hand, with the cockpit-end moving in unison. If the friction has not been reset, and if the pilot does not carefully follow every step of the checklist, it is possible to depart with them still loose. Condition lever and propeller lever friction is not too important, but power lever? Oh my goodness! Those levers will spring strongly back toward idle when the pilot’s hand moves to the landing gear control. If the pilot notices what is happening – of course that is usually the case – then the outcome is more comical than anything else as he tries to fly, get the gear up and tighten the friction while not letting the power be too low. But if the power lever migration (PLM) is not seen, then disaster can result. With both levers migrating back, but with the left almost always going to a lower power setting than the right, there may not be sufficient power to sustain flight. Also, the differential in power tends to lead the pilot to think that an engine has in fact failed. Furthermore, the marvelous autofeather system is rendered inoperative due to the migration of the levers.

Yet it is understandable (although, not excusable) for the pilot to never carry out the first step of his “Suspected Power Loss” procedure … advancing both power levers! Why? Because in his mind that was already done as the takeoff roll began. In other words, the “Power” and “Props” steps are already done in his mind, maybe even the “Flaps” step. So all he has to do (so he thinks) is get the “Gear” step done and watch autofeather do its job. (Or Identity, Verify and Feather manually if the airplane does not have the system.)

Please, please, please give proper attention to power lever friction before every takeoff!

Following on Tom’s words of wisdom, I have some other recommendations.

Double-check the Trims

If you look at the trim wheels in most King Airs they are a com­bination of numbered units, a “0” inside a box in the center and solid box on each extreme. It is very easy to look at a rudder trim or elevator trim and see what you think is center or zero, but more than once pilots have taken off with full trim only to realize it after rotation. In the King Air it is certainly controllable, but it can be a handful and many pilots try to fix what’s wrong instead of flying the airplane.

Be Thorough

In my opinion, the best way to approach the post-maintenance flight is to do it as slowly and methodically as practicable using the lengthy POH checklists in their entirety. In fact, you should do that twice … taking the aircraft to the shop and picking it up from the shop. By doing it before, you can discover any abnormalities that need the shop’s attention. Of course, doing it after can uncover the errors that may exist. In addition to the full preflight and run-up procedures, I also recommend an inflight Flow Pack, Leak Rate, and Cabin Altitude annunciator check accomplished before the Phase inspection to determine how the plane stands in these important areas. These checks are easier to perform in flight than in the shop’s hangar.

One more suggestion is to take off using approach flaps if airport conditions permit, as they almost always will. Recall that most, but not all, King Airs have a system that causes the landing gear warning horn to blow whenever the flaps are extended to a position greater than Approach when all three landing gear legs are not down and locked. I have observed numerous cases in which using flaps on takeoff causes the gear horn to blow as soon as the gear starts retracting. Why? Slight mis-adjustment of the triggering switch attached to the right inboard flap mechanism is the reason. The air loads that the flaps experience in flight usually ensure that the flaps do not extend far enough to trigger the horn. However, when the flaps are extended to Approach while taxiing or in the run-up area, the lack of air load may allow them to extend far enough to trigger the horn – something you don’t want during your short field takeoff!

Recording Results

Not long ago the only way that the pilot could communicate with the mechanic about some discrepancy he found was verbally or in writing. Of course, it is great to encourage the lead mechanic to accompany you on that first flight so that he can observe the same things that you are seeing, but often that is not feasible.

However, now we all carry one of the very best communication devices known to humankind … our smartphones. Having a video of the dancing engine gauge or of the autopilot overshooting the ILS localizer capture … wow, what an excellent way of showing what’s wrong! Remember to take advantage of this aid.

Closing Thoughts

It is my belief that any appropriately-trained, competent King Air pilot can successfully serve as the PIC during this most dangerous of common flights. However, I know that some pilots – although meeting all requirements and current in the aircraft – lack confidence to do a good job in this unfamiliar area. A couple of suggestions: First, practice complete walk-arounds and runups more often until the uncertainty and mystery is removed. Second, if possible, invite a more-experienced, more knowledgeable pilot to go along to help you with the tasks at hand. Even if the available pilot is not as experienced and knowledgeable as you wish, just having another set of eyes and a checklist reader to help you can be very worthwhile.

Be careful out there!

Kevin Carson is an A&P and manages the King Air Academy. Having flown about every King Air model and Beechcraft from T-34s, Bonanzas and Barons for over 30 years. He can be reached at: or (602) 551-8100. To learn more about the King Air Academy, go to

King Air expert Tom Clements has been flying and instructing in King Airs for over 46 years and is the author of “The King Air Book” and “The King Air Book II.” He is a Gold Seal CFI and has over 23,000 total hours with more than 15,000 in King Airs. For information on ordering his books, contact Tom direct at Tom is actively mentoring the instructors at King Air Academy in Phoenix.

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