By Robert N. Rossier, EAA 472091
This piece originally ran in Robert’s Stick and Rudder column in the January 2024 issue of EAA Sport Aviation magazine.
Not long ago, a pilot friend of mine may have narrowly missed having a bad day flying. During the preflight of the airplane she was planning to fly, something struck her as being amiss. She couldn’t quite see where the problem was, but somehow, something just didn’t look right. Things weren’t lining up the way they should.
She called a fellow pilot over to take a careful look at the airplane, and after a few minutes examining it, he agreed that something was out of whack.
Along with several other pilots, my friend had flown the airplane frequently in recent days and hadn’t noticed any issues. But in retrospect, it was difficult to determine what could have occurred, or when, or worse yet, why.
A Careful Preflight
We’re all taught from our early days of flight training to perform a careful preflight. Typically, we start with the procedure provided in the pilot’s operating handbook. Our instructors teach us to use that procedure, adding more details to be wary of.
Along the way, we might pick up additional items from our instructors, other pilots, mentors, articles, or hangar flying sessions. In the end, we may find ourselves methodically checking a laundry list of items: fuel quantity, fuel contamination, engine compartment, oil levels, pitot tube, pitot heat, static port, lights, flight controls, seat rails, propeller, spinner, landing gear, tires, wheels, and brakes.
We look for missing or corroded fasteners, missing cotter pins and safety wire, oil leaks, fuel stains, dings, dents, cracked seat rails, and other damage. The list goes on and on.
A Different Perspective
One trick I learned along the way and shared with my students is to end the preflight by stepping back behind the airplane and taking in the overall picture.
Look at the way the aircraft sits. Are the wings level or is one gear compressed more than the other? Are the fuel caps in place and lined up the way they should be? Is there any unusual twisting, bending, or warping of the wings, control surfaces, or empennage?
As one of my pilot mentors once explained, we want to look for signs that the airframe has been overstressed. If a pilot attempts aggressive maneuvers or aerobatic flight in an aircraft not certified for such, or encounters moderate to severe turbulence at too high an airspeed, the result might include damage to the airframe that could degrade its structural integrity. We can only imagine how such a scenario might play out.
Other damage might be caused by hard landings, unreported collisions, or impacts with birds or wildlife. And while we might observe such damage when we examine the aircraft from a close-up perspective, sometimes it’s the big picture view that reveals the subtle clues that something is amiss.
Years ago, a friend of mine was killed when a wing on his aerobatic airplane folded in flight. He was an experienced and conservative pilot. But he hadn’t known that a wing had been damaged perhaps by someone during a prior flight.
The damage might not have been visible from the exterior, but beneath the fabric, the wooden structure had been cracked. All it took was the right amount of load on the wing to cause it to fold up in flight. It was a tragic ending.
Issues With Aging Aircraft
Many of us fly aircraft that have been around the pea patch more than a few times and graced our skies for decades. Beyond what might be considered normal wear and tear, older aircraft can suffer from a host of maladies brought about by several factors.
Experts in the field identify external damage including corrosion and erosion, which affect the dimensions and surface finish of metal used in aircraft construction. Corrosion can occur in the form of pitting, which reduces material thickness and causes localized stress concentrations that result in cracking. If left unattended, such conditions can ultimately lead to material failure.
Over time, damage can also occur in the form of dents, abrasion, and wear. Those of us who fly older aircraft may see these conditions regularly and may not consider them to be a serious concern. After enough time, we might consider these defects as “normal.” However, these conditions can also degrade the functionality and strength of the material, and can result in fatigue failures.
Internal damage of metal components can result from creep and fatigue. Creep is described as the deformation of a metal that occurs over time during which the material is exposed to mechanical stress. Fatigue involves damage to a material that occurs due to repetitive cyclic loading.
Both creep and fatigue can reduce the structural strength of components and cause cracking and failure of the material. Especially if an aircraft does not receive the required maintenance actions to address these issues, degradation of components and structure of an aircraft can result in component failures and reduced structural integrity that erodes the design safety factors of the aircraft and its components.
The Big Picture
As it turned out, my pilot friend had identified what was likely a dangerous condition with the aircraft. When viewed carefully from the side in a crouched position, one could see that one landing gear had been bent slightly backward. Viewed from behind the airplane, it was also apparent that the wing on one side of the aircraft had the slightest hump above the landing gear strut attach point.
If viewed quickly and up close, it was easy to overlook the clues and completely overlook the damage. But by taking a step back and viewing the big picture, the damage became apparent.
It’s unclear as of this writing what had caused the damage to the aircraft, but among the possibilities are the aging aircraft factors. It turns out the aircraft was about 50 years old, with untold airframe hours and more than 40,000 takeoffs and landings.
Just as surely as drops of water can carve granite, the overwhelming cumulative effects of even “normal” stresses might conceivably cause such a failure. And that alone makes the case for a big picture preflight, particularly of our older aircraft.
We can speculate all we want about what might have occurred if my friend had not identified the damage. Perhaps a hard landing, a crosswind landing, or other stress would have caused the landing gear to fail on touchdown. Depending on the circumstances, it could be a catastrophic ending.
And who knows for sure if the integrity of the wing had been compromised, and what in-flight conditions might result in failure. Perhaps in turbulence, or a steep turn where the g’s are increased, the wing might have buckled or given way. Such an in-flight failure could easily result in a fatal accident.
The moral of the story is clear. The aircraft preflight is our primary opportunity to detect flaws and problems with the aircraft. Sometimes it’s the big picture view, rather than the close-up examination, where we can see where those problems exist. It only takes a minute or two to take that step back and examine the aircraft. It could be the best minute or two we spend in preparing to fly.
Robert N. Rossier, EAA 472091, has been flying for more than 40 years and has worked as a flight instructor, commercial pilot, chief pilot, and FAA flight check airman.