COMANCHE TECH TALK
While comanchepilot.com is basically dedicated to the Comanche, articles on any aviation subject from other owners and pilots are welcome. Meet guest author Tom Turner of the American Bonanza Society, whose work on safety issues has been quoted in previous Comanche articles.
PART 2 - TEST FLIGHT
by Thomas P. Turner, ABS
Your airplane's been in the shop for repairs. The annual inspection's complete. Maybe you've had it painted, or installed an upgrade. Whether the airplane was"down" for something as simple as an oil change or as intrusive as an engine change, it's wise to thoroughly check it before flying away from the shop.
In Part 1, we looked at the paperwork and preflight airworthiness checks you should make before accepting your airplane back from maintenance. This time, we'll take a look at your other post-annual duty: test pilot.
You've already made a *very* thorough Before Takeoff check…chances are reviewing the paperwork and performing an extensive, post-maintenance preflight inspection has taken well over an hour. Now, it's time for a short test flight to make sure everything still works the way it should. Hint: Make up a flight-specific checklist (see example) to make sure you cover everything on your test flight.
If the work you had done involved the engine or systems ahead of the firewall, you might consider starting the engine, noting normal engine indications, and immediately shutting down to conduct a "leak check." Keep this ground-run time short, especially if a cylinder had just been replaced, or if the entire engine is a replacement or an overhaul. It won't take long for leaks to become obvious, so start it up, check the gauges, and shut it down.
Once your airplane passes the leak check (or if you choose not to perform one), take off and climb to a safe altitude. Remain in day, visual conditions. Here's an idea: Bring a safety pilot with you to look for traffic while your eyes are in the cockpit checking systems. In fact, if you can bring the shop supervisor or the mechanic that did the work on your airplane, do it …he or she may be able to help diagnose those minor squawks that often crop up after the plane's been opened up.
Stay clear of the airport traffic pattern, but close enough to make it back if you lose power—flying the rectangular traffic pattern a thousand feet above pattern altitude is a good tactic. Check control feel, engine operation, and the use of all systems and avionics just as you had on the ground, and confirm a lack of surprises while in the air. Finish your short test flight by landing, taxiing back to the shop, and then completing another detailed inspection of the airplane. Bring any discrepancies to your mechanic's attention right away, and get them fixed (and re-tested) before accepting the airplane.
REAL WORLD EXPERIENCE
A little paranoia is a good thing. Here are some items I've found on post-maintenance acceptances, or seen when I've accompanied the owner on a post-maintenance check:
- Inaccessible manual landing gear extension handles, because of improperly installed interiors.
- Fuel selector handles that won't move to the "OFF" position.
- Inoperative alternators.
- Safety wire missing on emergency exit window latches.
- Mounting screws missing on the underside of ailerons.
- Ailerons mounted so that they could not reach full deflection.
- Landing gear doors reversed (right door on the left wing and vice versa), preventing gear retraction.
- Instrument air (vacuum) regulators adjusted well out of tolerance.
- Flap limit switches out of position, inhibiting flap movement.
- Autopilot disconnect switches that weren't hooked up.
As you can see, it's going to take time, and not a little patience on your part, to properly accept an airplane from the shop. Plan at least half a day, assuming all the paperwork's perfect and no squawks show up during inspection and test flying. If weather conditions are sketchy or nightfall approaches, put your flight off until the next day. Trust me—I've had total electrical failure in night, IMC in a Beech Baron during a flight home from annual inspection, because I was impatient and didn't perform a day/VMC test flight before leaving the shop. The time it takes to double check the work under controlled conditions is more than worth the stress and danger of impatience.
Most mechanics are highly skilled professionals. But like pilots, mechanics are people too, and subject to the same sorts of human-factors error as we who fly the airplanes. It's a team effort to return an airplane to service, whether the job was as big as an engine swap or as small as an oil change. Take the time to review the paperwork, check the airplane thoroughly on the ground, and to conduct a short test flight every time you pick up an airplane from the shop.
Here's a sample flight-specific, post-maintenance "Acceptance Checklist" I created for picking up an airplane from a paint and interior shop, with some additional work done during the down-time. Use it as a template for writing your own post-maintenance checklists.
Post-Maintenance Acceptance Checklist
a) Confirm that Airworthiness Certificate and Registration are in the airplane
b) Confirm that the Pilot's Operating Handbook is in the airplane
c) Check that overhead air valve has been fixed per agreement when I dropped off the airplane off
d) Check logbooks
i) Confirm they are in the airplane
ii) Check for entries for the paint and the interior installation
iii) Check for entries confirming the control surfaces were removed, painted, balanced and reinstalled
iv) Check whether there has been any change in empty weight, and if so, that a new Weight-and-Balance Equipment list has been completed, signed by an A&P mechanic, and inserted into the Pilot's Operating Handbook with previous editions marked as "superceded"
v) Check for logbook entry regarding the overheat air shutoff repair
e) TCM crankshaft inspection paperwork
i) With mechanic, review the inspection, reinstallation of propeller, and test run of engine
ii) Check engine logbooks and confirm entries for the above have been made and signed off
iii) Let mechanic review the logbook sticker provided by TCM, and stick the entry into the engine logbook
f) Install updated GPS database
2) Conduct a thorough preflight inspection, paying special attention to:
a) Control surface movement and security
b) Flap operation and security
c) Trim operation and security
d) Fit of cowlings, cowl flaps, and gear doors
e) Correct installation of manual landing gear extension handle (not blocked by spar cover)
f) Fit of door and window seals, and safety wiring of emergency exit handles
g) Verify all vortex generators are installed (note: one was missing when I dropped off the airplane. I left the repair kit and epoxy with paint shop and they said they'd replace the missing VG. Check that the repair kit is in the airplane)
h) Fit and finish of the radome (note: ask if it was removed during painting. If it was, radar and/or glideslope function may have inadvertently been impaired if wires came loose or were not properly reinstalled)
i) Signs of leaking, messy epoxy, or any other imperfections around the windshield and windows
j) General condition of paint and interior
3) Conduct a thorough, start-up and Before Takeoff checklist procedure, paying special attention to:
a) Proper engine, electrical and pneumatic indications immediately after start
b) Free and correct movement of the flight controls
c) Proper movement of the fuel selector valves
d) Proper operation of the flaps through all four "steps" of the limit switches
e) Proper operation of the autopilot and electric pitch trim using POH autopilot checklist
f) Free and unrestricted movement of the trim in all axes
g) Proper operation of all switches on the pilot's control yoke
h) Proper operation of all anti- and deicing equipment
i) Operation of the electrical equipment and avionics
j) Lack of "noise" on the Stormscope
k) Proper test operation of the weather radar
l) All circuit breakers remain "in"
4) Acceptance test flight: conduct a short test flight to verify proper operation, paying special attention to:
a) Proper engine operating indications
b) Proper electrical and avionics operation
c) Proper operation of the landing gear
d) Proper operation of the flaps
e) Proper autopilot and trim operation
f) If conditions permit, proper operation of the weather radar
g) If conditions permit, proper operation of the Stormscope
h) Test of glideslope reception
i) Correct "feel"—trim and rig; does the airplane properly respond to changes in power and configuration
5) Post-acceptance flight check: land and review with maintenance personnel:
a) Any squawks that resulted from the acceptance flight
b) Any unusual leaks, etc., found in a post-flight walk-around
c) Any other operational or business items
©2003 Thomas P. Turner for www.comanchepilot.com
Thomas P. Turner is a 3,300-hour ATP with over 2,100 hours as a CFI, and holds a Master's Degree in Aviation Safety. He contributes regularly to many aviation magazines, the American Bonanza Society journal, and www.ipilot.com. Formerly lead instructor for the Bonanza at Flight Safety, he served in the USAF, has worked as a production test pilot, ran a small FBO, and sold aviation insurance. An Oshkosh speaker and course developer for Embry-Riddle Aeronautical University, Tom's books include titles on "Cockpit Resource Management" and "Controlling Pilot Error," published by McGraw-Hill.