A Wing and a Prayer for a Classic Piper Arrow

Those of us seasoned in the world of aviation and airplanes know that stuff breaks. A cylinder loses compression. A fan blade cracks. A magneto fails. A hydraulic pump leaks. But do any of us for even a moment conceive that a wing might fail? Tragically, this is precisely what occurred on April 4, 2018, at Daytona Beach International Airport in Florida when the left wing separated from a 2007 Piper Arrow operated by Embry-Riddle Aeronautical University shortly after takeoff from a touch-and-go landing.

A commercial-pilot check ride was being conducted by 61-year-old designated pilot examiner John Azma, a 27,000-plus-hour ATP. The 25-year-old student, Zachary Capra, was a Navy veteran with 218 hours of total flight time. After some air work had been accomplished, the airplane returned to the traffic pattern, initiating a touch-and-go landing on Runway 25L.  Sometime prior to when the last radar track indicated an altitude of 900 feet during climb-out, the left wing separated from the airplane. The Arrow impacted the ground approximately 2 miles from the departure end of the runway. Neither pilot survived.

The airplane had logged nearly 7,700 hours of total time and over 33,000 hours of takeoff-and-landing cycles. The PA-28R-201 had been operated only by ERAU strictly as a flight school trainer, spending most of its life below 3,000 feet. The airplane had a maintenance record of 14 hard-landing events, with five occurring within the prior 24 months. Considering its occupation, the hard landings weren’t unusual. The appropriate inspections were completed for both the hard landings and the regular maintenance required of a Part 141 training facility. None of the procedural inspections would have revealed the fatigue crack that doomed the airplane.

Because the determination of probable cause was made early in the field investigation—almost conclusively at the crash site—the National Transportation Safety Board focused on metal-fatigue cracks within the main wing spar. The question of where and how the cracks originated dictated not only the course of the investigation but also the fate of the numerous Piper models affected by the resulting airworthiness directive. Extensive analysis—inclusive of electron-microscope observations, other flight school wing evaluations, inspection methodologies, US Air Force engineering participation, and metallurgy composition—was involved. In a frightening twist, an analysis by the Air Force of the airplane manufactured two serial numbers earlier—and part of the fleet at ERAU—determined that one of its wings was less than 2,000 hours away from failure.

A similar wing-separation event in 1987 on a PA-28-181 almost defined the current AD, but it was rescinded two years later because a determination was made that the accident airplane at that time was operated in a “severe” environment, utilized for pipeline patrol at consistently low altitudes. In other words, the wing separation was a result of operational circumstances seldom encountered.

Once the FAA was convinced the ERAU tragedy uncovered a serious problem that could affect numerous Piper models with the same wing-spar engineering installed, the “notice of proposed rule-making” process was initiated. The NPRM formulated the basis for the current AD, which brings us to my woes.

The AD includes a formula to calculate “factored service hours” for when a wing-spar inspection must be completed. It’s a simple formula that incorporates the number of 100-hour inspections performed, utilizing the theory that such inspections correlate to flight school airplanes and/or airplanes with higher cycles than personal-use airplanes. If the factored service hours equal 5,000 hours, an eddy-current inspection of the spar cap and outboard wing bolt holes must be performed. The wing does not have to be removed, only the two lower outboard bolts—not a major process for an experienced A&P.

My Arrow has only personal-use history, so if all was normal, my factored service hours would be approximately 250. For those of you who might remember Jumpseat’s April 2017 installment, a replacement with a salvage-yard wing was completed as a result of an inadequate hard-landing repair found by my mechanic friend in Connecticut after I had purchased the airplane. No documentation of the wing’s history was provided, either because it was lost or the salvage yard feared a liability issue. In this circumstance, the AD requires an eddy-current inspection regardless of factored service hours. Yay. But, wait, there’s more.

The original wing on the left side passed the inspection, but the replacement wing did not. Tiny gouges in the two bolt holes of the spar cap were found, possibly as a result of removal at the salvage yard. Yay, again. But, wait, there’s even more. 

Following the AD requirements and getting frustrating results attempting to obtain guidance from Piper, my mechanic, Josh Jackson, finally was able to contact a designated engineering representative near our Florida location. The DER directed the wing to be removed and a dye-penetrant test administered to locate fatigue crack(s). With none found, a new eddy-current inspection was performed. The right wing failed again.

An engineering order from the DER not only provided technical procedures to continue but officially deemed the Arrow unairworthy. Great. So, now what? Buy another salvage wing in a market that’s become overpriced because of the AD, with the possibility that it too will require a successful eddy-current inspection? And the replacement wing must be painted, notwithstanding its overall condition, i.e. dents, bruises, etc. Plus, the replacement wing must be compatible with the old fuel tank, ailerons and flaps. The dollar signs were starting to add up. Or…do I send out the wing for a complete spar repair? Is that the same money? 

So, with nothing to lose except a couple more decimal points [AC1] in my checking-account balance, the decision was made to continue with the engineering order, which consisted of carefully reaming out all the bolt holes of the spar cap—carefully—to within one-thousandth of an inch.

Well, the wing passed the third eddy-current inspection. Now we are in a holding pattern for approval from the FAA, through the DER, to allow wider bolts to be installed. Wider bolt holes require documentation in the form of an “alternate method of compliance.” My fingers and toes are crossed.

I won’t be the first and I won’t be the last PA-28 owner to confront this issue. I’m not sure that Piper and the FAA considered the collateral damage from the AD. It’s uncharted territory until more data is collected. For the moment, no template has been established for an AMOC in circumstances such as mine. 

That being said, the important goal is safety. Regardless, maybe I should just consider stamp collection.

Editor's note: This article originally appeared in the November 2021 issue of FLYING.