My latest communications with Aircraft Technician magazine concerned a mechanic/IA who had a problem with an owner of a PA-18 Piper Super Cub over an Airworthiness Directive (AD). The AD in question was AD 77-03-08 which dealt with Piper PA-18 and PA-25 wing lift struts corrosion inspection.
The AD references Piper Service Bulletin (SB) 528 as the approved method of compliance. The AD also requires recurrent inspections to be accomplished every five years. The IA pointed out to the owner that Piper voided SB 528 on Oct. 10, 1989 and superseded it with SB 910A. The latest Piper Service Bulletin is a lot tougher and limits the recurrent corrosion treatment and inspection time to every 12 months. The IA wanted to perform the AD with the new service bulletin, but the owner balked because of the additional expense and went to the FAA. The local inspector told the IA to comply with the AD as written. The law had spoken and the IA had to eat the time he spent working on the airplane.
Naturally, this did not sit well with the IA. He wanted to know who was right, and which service bulletin to use.
In this case, the FAA inspector was right. You can only use the service bulletin referenced in the AD (SB 528 in this instance). Yes, I saw the highlighted box at the top of the service bulletin in which the statement: “Piper considers compliance mandatory.” I also noted the statement that the technical contents of this service bulletin have been approved by the FAA.
To further clarify the decision of the inspector, consider this: A manufacturer’s service bulletin cannot change a regulation. Every FAA AD is a regulation issued under FAR Part 39. So every AD has the force and authority of law. That’s why FAA Airworthiness Inspectors get so upset when you miss an AD. In very real terms – you broke the law. And most likely, missing the AD endangered the safety of the aircraft.
A couple of other points that should be made concerning this subject:
• You can expect a new AD on Piper lift struts on or before April 1991. The new AD will affect all makes and models of Piper high wing aircraft.
• If you want to use the new service bulletin, you have another option. The owner could ask the FAA to use SB 910A instead of SB 528 as an alternate means of AD compliance. If the FAA contact is not mentioned in the AD (as is the case with AD 77-03-08) give the local office a call and ask for help.
• The waiting period for the new AD is due to the Administrative Procedures Act. The act requires public comment for any regulation that has an impact on the aviation industry. The total cost (impact) to the affected fleet of 20,000 airplanes will come to $20,000,000+ dollars.
• A new AD is required instead of revising the old one because it has been determined that all makes and models of Piper high wing aircraft are affected by this corrosion problem, not just PA-18 and PA-25 models. Furthermore, the new AD is a direct result of two fatal accidents.
As mentioned earlier, the IA was legally wrong. He must perform the AD as it is written or get an alternate means of compliance approved if he wants to use the new service bulletin. His concern for safety, however, cannot be criticized.
This article first appeared in the January/February 1991 issue of Aircraft Technician
