The AD, which takes effect February 16, calls for operators of affected aircraft to calculate the service hours of wing spars from maintenance records in accordance with a prescribed formula, and if necessary, inspect lower main wing spar bolt holes for cracks, and replace any cracked spars.
The list of affected models includes the Piper PA–28-151, PA–28-161, PA–28-181, PA–28-235, PA–28R-180, PA–28R-200, PA–28R-201, PA–28R-201T, PA–28RT-201, PA–28RT-201T, PA–32-260, PA–32-300, PA–32R-300, PA–32RT-300, and PA–32RT-300T airplanes. In some cases, only some serial numbers come under the AD.
The NTSB determined that the probable cause of the April 4, 2018, accident in Florida involving a Piper PA–28R-201 operated by Embry-Riddle Aeronautical University was metal-fatigue cracking associated with flight training maneuvers and frequent landing cycles.
“The FAA estimates that this AD affects 5,440 airplanes of U.S. registry,” the AD said. The estimate is based on a sample survey indicating that about half the 10,881 airplanes of U.S. registry with affected serial numbers “will have reached the qualifying 5,000 hours [time in service] necessary to do the required logbook review.”
“The FAA also anticipates that the majority of those airplanes will not need an inspection after the logbook review,” it said.
The AD, as originally proposed, would have covered approximately 20,000 airplanes, as AOPA noted in formal comments on the proposal, urging the FAA to “rethink the risks of ordering invasive inspections of numerous older aircraft.” The NTSB also expressed concern about the risks of ordering invasive inspections, as AOPA reported in June 2020.
The FAA followed up its proposed AD by reopening the period for public comment and reducing the number of affected aircraft by about 8,000 airplanes.
AOPA and Piper Aircraft Inc. requested that PA–28-151, -181, PA–32R-300 and PA–32RT-300T models be removed from the list, noting structural differences. The FAA declined, citing load-analysis studies, and also dropped its earlier proposal to exclude the Piper PA–28-161 from the affected-model list.
According to the AD, estimated compliance costs will be $255 per aircraft to review maintenance records and calculate factored service hours, and—for aircraft requiring inspection—about $1,045 for inspecting the aircraft and reporting the results to the FAA and Piper Aircraft Inc.
The FAA noted that the inspection reports will provide additional data for estimating “the number of cracks present in the fleet” and considering any further rulemaking actions.