|Taking Care of Your Avionics|
|Written by Jacqueline Shipe|
The technology available today allows for some sophisticated communication and navigation equipment in aviation. Panel-mounted GPS units and glass cockpits have created an almost space-age look in today’s modern instrument panels. Most of the newer equipment makes navigating and communicating much easier for the pilot, which help to increase safety. Although avionics equipment can be very expensive to install, most upgrades do increase the overall value of an airplane, usually by about half the cost of the upgrade.
There are some simple things that an airplane owner can do to help maintain his or her avionics and reduce costs in the process.
Excessive heat is an enemy of all electronics equipment. Summertime temperatures and any heat seeping through ductwork from the engine compartment combined with the heat generated from the avionics themselves can create a very hot environment under the panel. Cooling fans with connecting hoses can significantly reduce the operating temperatures of the avionics stack. Lower operating temperatures will greatly extend the life of the equipment. Cooling fans typically are not too complicated to install, and their cost is relatively low compared to their benefits.
A clean and tidy panel area also increases the longevity of aircraft radios. Dust created from old, crumbling insulation and other sources can coat the units, causing them to retain more heat; additionally, the dust can get inside the radios themselves. Old insulation can also cover and conceal corrosion on the frame and firewall. Loose wires that are not properly bundled and secured can rub against the frame and cause a short circuit. Also, they could cause binding of the controls, depending on how they are routed. The wires from the ignition switch to the magnetos need to be especially secured to prevent chaffing, which could lead to grounding out a magneto. After completing any work under the panel, the controls should be moved and fully deflected in all directions to be sure they are not obstructed.
The transponder and encoder require periodic inspections. FAR 91.215 states that installed transponder equipment must meet certain performance requirements. FAR 91.413 states that transponder equipment isn’t supposed to be used unless it has been tested within the preceding 24 months and found to comply with the appropriate sections of FAR 43 Appendix E and Appendix F. Some pilots have assumed that as long as the airplane wasn’t IFR-certified that the transponder didn’t have to be tested. The regulations state that it is not supposed to be used in flight at all unless it has been tested, even if the flight is conducted under VFR. Even if the equipment has been tested, if air traffic control is showing an altitude reading on its screen that is more than 125 feet different than the reading shown to the pilot on the altimeter, the encoder or altimeter is out of adjustment. Most encoders read differently once they are warmed up after being turned on for a short period of time; usually, they are more accurate.
Clean antennas work better. Antennas that are mounted on the belly usually get grimy from the blow-by oil coming out of the breather. Cleaning the antennas regularly will cause them to get better reception. Some marker beacon antennas are belly-mounted and include a curved piece of metal followed by a long straight section. There is a wire that is clamped to this type of antenna. Marker beacons that are not sensitive enough or too sensitive can be adjusted at the antenna by moving the location of the clamped wire on the antenna forward or aft. It’s best to mark the original position before adjusting it, and a short movement makes a relatively large difference.
Equipment that quits intermittently can be hard to troubleshoot. If there is reasonable certainty that a particular unit is working properly internally, sometimes intermittent problems can be traced to a circuit breaker. Older circuit breakers can fail and open the circuit without actually popping. They can also fail and not pop, even if there is a short. Breakers are usually not too expensive, and sometimes they’re worth replacing just to eliminate the breaker as a possible source of trouble. One particular airplane had a Garmin transponder that would work for about an hour into flight and then quit. The transponder was sent out for inspection and was sent back with no defects found. Everything would work fine on the ground; the unit was getting power and operating normally, but it would fail at around the same time period into each flight. Finally, the circuit breaker was replaced, and the problem was eliminated.
Sometimes, if there is a problem with a particular component failing internally, buying a used unit can be one of the less expensive options for solving the problem. Always check several prices and see what the return policy is before buying. There are several salvage yards, and many items are bought and sold on the internet. One advantage of buying from a salvage yard is that a person can be relatively sure that the parts aren’t stolen. Although it’s very rare, eBay has been used to sell stolen radios.
Last, but not least, operating your equipment and your airplane helps to eliminate moisture and increases longevity, not only of the avionics, but of the entire airplane.