Getting Older: A best practices guide for aging aircraft

Nov. 1, 2003
It's 4:50 a.m. on the first workday in the second week of October. The clock radio pops on, right in the middle of a country and western song sung by a Patsy Cline wanna-be.

It's 4:50 a.m. on the first workday in the second week of October. The clock radio pops on, right in the middle of a country and western song sung by a Patsy Cline wanna-be. As the wailing assails my ears, I intuitively know that the best part of my day is over. So with a superior effort, I shove an arm out of the warm covers and smash the "off" button on the radio with a badly aimed fist.

Since I am on the serious side of 60, experience dictates that before I dare to stand up, I must sit on the side of my bed, and take a minute to carefully check out all my systems. First I wiggle my toes to see if the feet are still attached and to make sure that one or both of my limbs are still not asleep. OK, they work. Arms and most of the fingers working? OK. Rotator cuffs still rotating? OK. Heart beating at least a couple of times a minute? OK. Are the eyes open - seeing is optional? OK. Next, I take a couple of deep breaths to wake up my lungs and reward myself with a cough. System check completed I then slowly stand up, wait for my internal gyros to come up to speed, and then make my way in the dark to the bathroom with all the grace and coordination of the mummy Imhotep.

Turning on the light, I lean on the sink with both hands and stare red-eyed into the bathroom mirror and am surprised to see my father's reflection staring back at me. Alarmed, I straighten up; but I am still held captive by the image in the mirror. Standing there on the cold tile floor, I am forced to inventory the ravages to my body caused by mankind's most common inherited genetic disorder. It is called aging. I can no longer continue to lie to that face in the mirror. Today was the day I realized that I am no longer the man I always thought I was.

Airplanes, like people also age with time. And like people, it is sometimes hard to tell just by looking if an airplane has been flown hard and fast and put away wet or treated each and every day with tender loving care.

The average age of a general aviation, single- engine aircraft, in this country is 34 years old, with the age for multi-engine recips sitting just shy of 30 years. That means that half the GA fleet is older than 30 and the rest is younger, with the majority of the bell curve sitting in between the 25- to 45-year-old age bracket. We have approximately 180,000, active GA airplanes registered. So if I do the math right we have approximately 90,000 aircraft that have been working and flying for 30 plus years. That's a long time defying gravity. If airplanes were people most of the GA fleet would have been retired by now. I am sure that Clyde Cessna, Walter Beech, and Bill Piper never thought the aircraft they built in the '50s and '60s would still be flying today.

The FAA has been concerned about our aging civilian fleet. In 1991, the FAA started a comprehensive program to address age-related problems with air transport aircraft. Several ADs and required inspections for specific aircraft were some of the actions taken because of this ongoing program to look into age-related problems plaguing the air carrier fleet. Recently, the FAA and industry groups joined forces and put together a Best Practices Guide for Maintaining Aging General Aviation Airplanes. This guide can be downloaded off of:

The FAA and industry both recognized that like people, airplanes, especially training airplanes, can age 10 years in one calendar year. On the other hand, some aircraft age gracefully over the decades, always looking factory new. One of the major factors between the two kinds of aging processes is the quality of maintenance the aircraft receives. And like older people, older aircraft need additional maintenance in order to perform as advertised. The FAA's Best Practices Guide stresses this idea of good maintenance practices by recommending two specific areas to help assess the condition of an aircraft. They are: aircraft record research and special attention inspections.

For the purposes of this article let us assume that you are a mechanic, who has to do a pre-buy inspection on a 43-year-old airplane.

Records research
For many owners and mechanics, an in-depth records review is about as exciting as watching the water in your denture cup turn blue, but it has to be done. The FAA Best Practices Guide recommends the following documents to review:

Type data/specification sheets: The aircraft's type certificate data or specification sheet is in reality the aircraft's birth certificate. These documents have all the relevant facts and figures for your aircraft, engine, or propeller. They list required equipment, optional engines and accessories, approved alterations, etc. You can access the FAA website for type certificates at:

Logbooks: You must lock down the total time in service for the airframe, engine(s), and propeller(s). These TC products' time-in-service will serve as your research baseline. Next, review the AD list and check for compliance, including ADs requiring repetitive inspections. While most mechanics and owners stay up to date with ADs for the airframe, engine, and propeller, very few spend the time to check ADs for the accessories. For example, the last time I checked, there were 14 ADs against seat belts. You can review ADs on the FAA website at

Supplemental Type Certificates (STC): STCs are major changes to the aircraft, engine, or propeller's type design and require a Form 337 to be sent into the FAA. The majority of STC's are for major alterations such as avionics installations, installing different engine and propeller combinations, or modifications to the airframe such as interiors, camera mounts, etc.

What most owners and mechanics do not realize is that an STC approved by the FAA after January 1981 has Instructions for Continued Airworthiness (ICA) as part of the STC package. These ICA are, in fact, a maintenance manual for the components installed under the STC. Any inspections called out in the ICA must be performed at the required interval usually during the annual inspection.

For example, you check the logbook and find that a three-axis autopilot was installed in this aircraft in 1990, I am willing to bet the ICA for that autopilot installation requires that the bridle cables that attach the autopilot servo to the primary control cables must be checked for the proper tension. If no inspection is recorded, then the aircraft is not airworthy. So you have to make sure all the ICA are complied with. This requirement also includes FAA Field Approval ICAs for alterations performed after September 1999. You can view all kinds of STC information at the FAA web site:

Service bulletins and letters: A good source to find information on potential aging problems is the manufacturer's service bulletins and letters for your make and model airplane. These bulletins and letters serve as a heads up for in-service problems that could be precursers for an AD or they could just be an overall notification for a product improvement.

Other information sources: Pull up your aircraft on the FAA's Service Difficulty Reports (SDR) system at: Punch in your make and model and the system will give you a list of all the problems other mechanics have found on your aircraft. It's like having a crystal ball in your toolbox. Another good, but largely untapped source of where to look for information, are the probable causes of aircraft accidents identified on the National Transportation Safety Board web site: You will be surprised at how many accidents could have been avoided by knowing where to look during the preflight or annual inspection. A couple of other good sources are the FAA's General Aviation Airworthiness Alerts and FAA's Special Airworthiness Information Bulletins at: and clicking on the applicable hot link.

Special attention inspections
The Best Practices Guide strongly urges maintainers of older aircraft, to take the information gleaned from the records search and use it to prepare a checklist for a special emphasis inspection. This special inspection should zero in on aircraft systems and components that are susceptible to aging.

Examples of such systems are: wiring, instruments, fuel system, and flight and engine controls. Appendix 1 in the guide has identified a generic list of these systems to help you get started preparing a personalized special inspection checklist for the aircraft in your care.

The guide recommends that the mechanic should be aware that not all of these checklist items need to be done every year. Particularly difficult inspections such as inspection of wing spars and fuel tanks could be scheduled every five years or so depending on flying time between inspections and environmental variables, such as industrial pollution, exposure to saltwater, or extreme cold or hot weather.

Many actual and potential problems areas caused by aging have already been identified by organizations known as Aircraft Type Clubs. These organizations are composed of aircraft fanatics that have an ongoing love affair with a particular make and model of aircraft. Over the years, I have dealt with several of these organizations and I am pleased to report that these folks know their aircraft inside and out and are quite happy to provide mechanics and owners with an easy access to all available data on their particular aircraft.

Several type clubs will sell you, for a minimum fee, the TC production drawing for the aircraft no longer in production. Having the manufacturer's approved drawing is nice to have when doing a major repair or making a replacement part. A list of type clubs and contact information can be found at

In closing, I offer a suggestion: Run off several copies of the guide and hand them out to owners of aircraft built prior to 1973. Tell them to give the guide a good read, and maybe one or two of them might decide, in the interest of safety, to have you do a special inspection on their aircraft. After all, if airplanes are like people, then they need a little more special attention as they get older, especially if they want to last a little bit longer. Which reminds me, I have to sign off right now. I have just enough time left in my day to make a doctor's appointment and schedule my annual special inspection and blood test.

About the Author

Bill O'Brien