Retrofit Checklists: Test Flying, Familiarity

Retrieving an aircraft from the shop after major avionics work requires a meticulous preflight, flight testing and a solid understanding of the interface.


The fragile relationship between avionics shops and aircraft owners is sometimes stressed at the end of a project. Thats partly because some owners have unrealisticexpectations, assuming the aircraft will be released right after a flight test.

On the other hand, shops create stress for themselves when they overpromiseand offer the impression that work on the aircraft is finished when in reality, it might still require testing, tweaking and more work following the flight test.

You can avoid this stress, while increasing safety, by approaching the delivery process with the proper mindset. This includes crafting your own delivery checklists of items to look for before, during and after the shake-down flights with the new equipment. You can also make the delivery process easier by studying how to operate the new equipment, working closely with the shop during the project and not scheduling important trips until you are certain everything works the way it should.

Planning The Pickup

You can plan the delivery process early. Good shops will gather pilot guides and training material for the new equipment and offer them to the customer well in advance of delivering the aircraft. This is a productive way to pass the time while the aircraft is down. The goal is to become familiar with the equipments operation so you can effectively and safely fly the aircraft on the test flight. Youll find that some pilot guides are more concise than others. Your early studying might presenta challenge, since you wont have the real equipment to work with as you follow along with the manual. Manufacturers such as Garmin, for example, recognize this and supplement the GTN-series navigator manual with a training CD. We think the operating manual for the Aspen EFD1000 display is well-written, presentingreal-world flight scenarios, while covering system functionality in detail. Garmin presents similar scenarios in their manuals.

Delivery Day

Next on the checklist should be the timing of the delivery. If you can avoid it, dont retrieve the aircraft from the shop-especially when the delivery requires a flight test-when you are short on time. Shop schedules vary, but most shops wont want to begin flight testing late in the afternoon, in case there are repair issues that need to be addressed. Remember, a flight test is just that-a test of the equipment.

Theres no guarantee that you will fly the aircraft home that day. Youll set yourself up for disappointment if you expect otherwise, and youll be pleased if you can take it home that day. If the shop performs thorough ground testing, there should be few, if any, problems to address once they pull the trigger on a fly-off.

Plan on performing the flight test during day VFR conditions. Many shops have stringent requirements written into their Repair Station manual, which covers the conditions for which they can conduct maintenance flying. You might need to make an honest assessment of your currency. If the aircraft was down for weeks or months, are you confident that your skills are sharp enough to handle the workload that tags along with maintenance flying? The technician you are flying with will bewell aware-and apprehensive-of this additional risk. Consider loggingsome takeoffs and landings before carrying the technician as a passenger.

Shops and Training

Your delivery checklist should include a solid plan for obtaining quality avionics training. Most avionics shops arent in the flight training business. The better shopshave people on staff who have exceptional product knowledge and know how to operate the equipment in the real world. These people often mentor the customer and will likely fly shotgun on the flight test. But this doesnt make them flight instructors, and it doesnt make them responsible for training customers.

If you dont feel you are up to the task of flying the aircraft after major avionics work-particularly on a maintenance flight test-we think the best option is to put your piloting pride aside and hire someone to take your place. Dont forget, however, to address an insurance issues that might come into play with someone else piloting your aircraft. Remember, too that a maintenance flight-test is not to be considered a training flight.

All Eyes On Preflight

You should craft your own walkaround and cockpit preflight checklist to accomplish as you prepare to fly. Approach this with a skeptical mind-set, especially if there wasmaintenance work accomplished in addition to the avionics work. The exterior walk-around should have you looking for properly secured cowlings, inspection plates and any securing hardware that might be missing or loose. Turn on all of theexterior lighting-systems that are easily missed during a walk-around but susceptible to failure after a large teardown. While youre at it, check the stall warning horn.

Pay particular attention to the pitot tube and static ports. If there was pitot and static system testing that took place, its not uncommon for technicians to tape the ports to pressurize the static system. Hasty techs forget to remove the tape. Since the aircraft has probably been sitting for a while, look hard at fuel samples-and fuel quantity.

Since the shop likely performed sizeable amounts of ground running, dont assume the tanks have the liberal amounts of fuel they had when you dropped the aircraft off. One technician we spoke with had a chilling tale of dealing with fuel exhaustion on a flight test-and with a frazzled owner who swore he had enough when he dropped the aircraft at the shop.

Paperwork is an important and sizeable part of major retrofits. Ask the shop to go over all of the paperwork they revised and produced in support of the installation. This should include updated weight and balance reports, equipment list revisions,flight manual supplements, FAA 337 paperwork and updates to pilot operating manuals. Make sure the aircraft registration, flight manual and airworthiness certifi cate are in the aircraft.

Your cockpit checklist should include testing critical items. The first area you might look at is the circuit breaker panel and bus-tie configuration. A circuit breaker may be the only way to remove power from a new system and you should know exactly where it is. Speaking of power and electrics, check that the fi re extinguisher is in the aircraft. This and other cabin accessories are often removed for storage during the installation.

If the aircraft is equipped with an autopilot and electric pitch trim system, follow the manufacturers procedures for preflighting the system. These procedures should include servo disconnect, proper pitch trim movement and correct control surface drive. Make a methodical sweep from one side of the panel to the next, checking instrument panel and cabin lighting, testing annunciator lamps, while becoming familiar with newly installed switches and controls. Power up the avionics andlook for system warning messages that may point to failing data ports and databus errors. These errors indicate communication problems between interfaced equipment. You might be able to check for valid and accurate Mode C altitude reporting, if the transponder displays pressure altitude.

What Works?

For the flight test, the tech likely has a plan for testing the interface. A maintenance flight test should preclude with a briefing that establishes who is going to do what tasks during the test. Let the technician evaluate the equipment and push the buttons while you manage the aircraft and watch for traffic. In general, flying a few instrument procedures along with reasonable amounts of cruise flight should be sufficient to test the entire suite. Youll be testing comm radio performance, navigation system accuracy, autopilot coupling, heading system accuracy and otheritems that are spelled out by a given manufacturers testing procedures. Experienced techs know what to look for.

When you make arrangements to pay your bill, keep in mind that money matters can be one of the biggest source of stress between shop and customer. This can be avoided with good communication If the shop presented you with payment terms that include payment upondelivery of aircraft, its expected that you show up with payment. As muchcomradery that may exist between you and your shop, dont forget thatthe shop is still there to make a living. Deal with the financial part of the work before the flight testing so it doesnt distract from the delivery process. Last, flying behind a retrofitted panel could be like flying a different aircraft. Be ready to overcomea learning curve before you tackle complex missions.

This article appeared in the Novemebr 2012 issue of Aviation Consumermagazine.