FAA has reiterated that manufacturers cannot specify where inspections and other mandatory work on their products is performed, but left open the question of what fair compensation is for the proprietary maintenance instructions that a repair station may need to do the work.

The interpretation came in response to a letter from repair station Piedmont Propulsion Systems (PPS), which told FAA that some propeller manufacturers were requiring that certain work be done at their own facilities. As a result, the manufacturers were not allowing PPS to acquire the related Instructions for Continued Airworthiness (ICA)—or maintenance manual sections.

FAA underscored that manufacturers—specifically design approval holders (DAHs)—can’t dictate where work on their products is done.

"The holder of a design approval may not restrict the performance of ‘mandatory’ inspections and repairs to only facilities it specifies," FAA wrote in a March 31 letter to PPS.

The letter references past interpretations emphasizing that ICA must be made available to any repair station with an "impending need" for them--such as "ongoing work" on the product in question.

The PPS letter does not tackle the sticky question of what constitutes fair compensation for ICA. "Clearly an issue could arise where a fee charged by a DAH could be so exorbitant as to effectively make the ICA unavailable," FAA notes, referring to an August 2012 response to an Aeronautical Repair Station Association (ARSA) request that discusses the issue in more detail, but does not set a firm baseline.

The ICA issue continues to be significant as manufacturers seek to capture more of the aftermarket work on their products, while independent MROs fight to keep revenue coming in.

FAA’s interpretations have made it clear that independent MROs have just as much right to do work on products as OEMs or designated service centers.

However, the agency has established some parameters that independent MROs believe are burdensome. For instance, while FAA make clear that ICA must be made available to shops that need them, it has declined to set the baseline for what defines a need. The agency has concluded that simply being a repair station capable of doing the work in question isn’t justification for acquiring ICA.