The American Federal Aviation Administration (FAA) announced this week that they are modifying the proposed wing spar inspection airworthiness directive (AD) by adding some models and removing others.
The original proposed AD called for the eddy-current inspection of the lower main wing spar cap of numerous PA-28 models. This action was prompted by the fatal wing separation incident involving a PA-28R-201 in Florida in 2018. Investigators determined that fatigue cracking in an area that is visually inaccessible was the cause.
The FAA is now proposing to add three more Cherokee models that it considers to be at high risk to the proposed AD, the PA-32R-300, PA-32RT-300 and PA-32RT-300T, and deletes five previously listed models that it considers to be at lower risk, the PA-28-140, PA-28-150, PA-28-160, PA-28-161 and PA-28-180. The FAA says that this will reduce the number of affected airplanes by approximately 8,800.
“Those aircraft models with calculated wing loads greater than or equal to 95 percent of baseline are considered at-risk and are included in the new effectivity,” the FAA states in the supplemental notice of proposed rulemaking (SNPRM) document.
The SNPRM includes a formula for calculating what it refers to as factored time in service for determining whether a specific aircraft will be subject to the AD.
The FAA received feedback after publishing the original NPRM from a number of parties, including Piper, with concerns that the removal of the wing attachment bolts for the purpose of conducting the bolt hole inspection would cause maintenance-induced damage to the aircraft, making the exercise not worth any benefits gained by the inspection. Piper commented that some of those who have already voluntarily conducted the inspection reported that the intervention caused damage to the bolt holes. However, the FAA disagreed and will not change their position.
Other respondents requested that the FAA consider other forms of inspection that are less intrusive, such as a borescope or dye penetrant inspection. The FAA did not agree with those proposals either and maintains that the inspection must be done using the eddy current method.
The full SNPRM document is appended below.
Photo credit: NTSBSNPRM 2020-11343