The FAA has proposed a new Airworthiness Directive for inspecting wing spars for certain Piper aircraft.
Models affected include: PA-28-140, PA-28-150, PA-28-151, PA-28-160, PA-28-161, PA-28-180, 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, and PA-32-300.
FAA officials estimate that 19,696 aircraft will be affected by the AD.
According to FAA officials, they received a report of a fatigue crack found in the lower main wing spar cap on a Piper PA-28R-201. An investigation revealed that repeated high-load operating conditions accelerated the fatigue crack growth in the lower main wing spar cap. In addition, because of the structural configuration of the wing assembly, the cracked area was inaccessible for a visual inspection.
The FAA determined that the number of 100-hour inspections an airplane has undergone is the best indicator of the airplane’s usage history.
“Using the criteria in FAA Advisory Circular AC 23-13A, ‘Fatigue, Fail-Safe, and Damage Tolerance Evaluation of Metallic Structure for Normal, Utility, Acrobatic, and Commuter Category Airplanes,’ we developed a factored service hours formula based on the number of 100-hour inspections completed on the airplane,” FAA officials said in the proposed rulemaking document. “A review of the airplane maintenance records to determine the airplane’s usage and the application of the factored service hours formula will identify when an airplane meets the criteria for the proposed eddy current inspection of the lower main wing spar bolt holes.”
Only an airplane with a main wing spar that has a factored service life of 5,000 hours, has had either main wing spar replaced with a serviceable main wing spar (more than zero hours TIS), or has airplane maintenance records that are missing or incomplete, must have the eddy current inspection.
This condition, if not addressed, could result in the wing separating from the fuselage in flight.
FAA officials add they consider the AD an “interim action.”
“The inspection reports will provide us additional data for determining the cause of the cracking. After analyzing the data, we may take further rulemaking action.”
Estimated Costs of Compliance
To review maintenance records and calculate factored service hours, the FAA estimates two work hours at $85 an hour for $170 per airplane. Total costs for the U.S. fleet: $3.3 million.
The estimated costs to do the eddy current inspection, if needed, is $147.50 per wing spar, according to FAA officials. Add to that another $85 work hour for reporting the results to the FAA.
If the main wing spar needs to be replaced, estimated labor costs — for 32 work hours times $85 an hour — is $2,720 per wing spar. Add to that the costs of the part — $5,450 — and the total is $8,260 per wing spar.
Want to Comment?
Comments must be received by Feb. 4, 2019. Include “Docket No. FAA-2018-1046; Product Identifier 2018-CE-049-AD” at the beginning of your comments.
- You can comment online at at the Federal eRulemaking Portal
- Fax: 202-493-2251.
- Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
- Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
All comments will be posted without change to the AD at Regulations.gov.