Advanced Preflight After Maintenance
#FlySafe GA Safety Enhancement Topic
The General Aviation Joint Steering Committee (GAJSC) and the National Transportation Safety Board (NTSB) have determined that a significant number of general aviation fatalities could be avoided if pilots were to conduct more thorough preflight inspections of aircraft that have just been returned to service. In-flight emergencies have been the direct result of maintenance personnel who have serviced or installed systems incorrectly. In many cases, although the maintenance personnel made the initial mistake, the pilot could have prevented the accident by performing a thorough or advanced preflight check.
Did you know that maintenance-related problems are one of the most deadly causes of accidents in general aviation? Contributing to this is a pilot’s failure to identify maintenance discrepancies because of a lack of knowledge and improper techniques used during the preflight of the aircraft.
What Can Pilots Do?
Conduct an Advanced Preflight that goes beyond the normal preflight checklist. Advanced preflight is a program that helps you become more aware of all the safety-related data on your aircraft, and focuses on a detailed approach to your preflight inspection, based on your aircraft’s maintenance history. While this requires some time, consider developing an additional items checklist that can be used in conjunction with the aircraft’s preflight checklist for all future preflight inspections. It is a valuable tool whether you own, rent, or borrow an aircraft.
Put Yourself in the Right Mindset — assume that there is something wrong, even if you used the best mechanic. Mechanics typically do an excellent job, but if you assume that all is right, you’ll miss catching possible mistakes, worn or improperly rigged items, or whatever else might be wrong. Always look over any part of the aircraft that has maintenance performed on it. You need to pay VERY close attention when preparing to fly for the first time after an annual inspection.
Use Your Senses, and a notepad, to write down anything you sense is not right. LISTEN to the airplane (not just the engine!). Do you SMELL anything abnormal? Fuel? Oil? Does it vibrate more than usual (FEEL)? Do you TASTE (or smell for that matter) any of that acrid smoke that comes with burning electrical items? Step 10 to 15 feet back from the airplane. Does anything LOOK out of place? Be prepared to abort takeoff if something goes wrong or doesn’t feel right.
Before Your First Flight After Maintenance:
✓ Learn all you can about the maintenance that was performed.
Discuss all work that was done with the mechanic and ask what to look out and watch for during the first flight. They should properly document all maintenance and operational checks performed, any maintenance required, and any items that may need to be monitored prior to the next scheduled inspection. But do not just accept that the work was done. Ask the questions: What was touched, repaired, or replaced, and what was accomplished?
✓ Know what systems or structures were repaired or replaced during maintenance. Don’t assume the part(s) replaced are the only parts removed. Often disassembly needs to be done to get to the inoperative part.
Ask what was removed and/or disconnected to facilitate the work performed. In many cases, seemingly unrelated external parts, or more importantly, internal parts, must be disassembled to perform inspections, repairs, or replacements. For example:
- Upholstery / seats, tracks, floors / emergency exits
- Interior and exterior access panels especially in hard-to-see places of the aircraft
- Yokes / control cables, linkages, and surfaces
- Equipment and appliances / wires and connectors
- Hydraulic / vacuum / brake / pitot and static / fuel lines
✓ Pay particular attention to trim positions. If work was done directly on the trim system, check for unimpeded flight control surface deflections and make sure the deflections go in the proper direction!
Fully understand which way the trim tab needs to travel when trim input is given to the control. Pilots have discovered (right after the aircraft lifted off) that one of the trims was left in a position they weren’t expecting.
✓ Make sure all inspection panels are secure and their fasteners are tight.
Inspect all control fasteners for missing cotter pins. A missing cotter pin can cause the nut to loosen and fall off, causing the control surface or trim tab to move or flutter on its own. Inspect locknuts, making sure the bolt or stud extends at least the full round or chamfer through the nut. Flat end bolts, studs, or screws should extend at least 1⁄32 inch (or 1 and ½ threads) through the nut. Check all visible bolts. If there is a hole in the bolt head, it may require safety wire in it. FAA Advisory Circular 43.13–1B outlines the various locking methods and the proper safety wiring procedures. You can also see our Safety Wire #FlySafe topic here:
✓ Check fuel tank for water, sediment, and proper fuel grade.
Use a sampler cup to drain a small quantity of fuel from the fuel tank sump quick drain valve placing the cup in front of a white background (blue sky or background makes it more difficult to see what’s in the fuel). Pull out the strainer drain knob for about four seconds to clear the fuel strainer of possible water and sediment.
✓ After an oil change, always check the engine oil level to ensure it has the proper amount of oil.
Remember that most oil filters will take up to a quart of oil to fill it. Even though the maintenance facility may have added eight quarts of oil, the dipstick will only indicate a little over seven in the sump after the run up. Remember oil serves two purposes. One for lubrication and the other is for cooling of the engine.
✓ Always check your logbook and paperwork prior to flight to ensure the correct records have been entered.
Look over the records to determine what areas of the aircraft had maintenance performed on it. Remember to check for proper log entries for the work performed and the return to service. If this isn’t done, the aircraft isn’t legal to fly. Always ensure you have the correct documents (e.g., airworthiness certificate and registration) onboard.
✓ If you see a warning tag or sign on the aircraft sign out clipboard, status board, or on the aircraft itself, DO NOT FLY THE AIRCRAFT!
Check with the maintenance facility prior to taking the aircraft. It’s possible the work was not completed when expected.
✓ Participate in, or observe your mechanic perform, an annual or 100 hour inspection.
It’s a great way to learn about your aircraft’s systems, components, and any areas prone to failure or weakness.
Download this story as a printable PDF. For more GAJSC safety enhancement topics, click the FlySafe image.