Hello Avmgr and Maint subscribers,
The purpose of this email is to ascertain what your interpretations as aviation department managers and maintenance personnel are concerning the FAA’s National Policy Notice N 8900.410 Effective Date: 3/31/17, regarding SUBJ:
Clarification of Inspection and Overhaul Requirements Under Part 91, which will be incorporated into FAA Order 8900.1 before this notice expires 3/31/18.
Please refer to the following link: https://www.faa.gov/documentLibrary/media/Notice/N_8900.410.pdf for the complete text.
Paragraph 4. Background. There have been several recent issues surrounding the interpretation of whether compliance with the manufacturer’s recommended time between overhaul (TBO) intervals are required under Part 91.
Paragraph 5. Discussion. a.(1)(b) Overhauls are Maintenance. By definition, overhauls are a form of maintenance, not inspection, and are not included in an inspection program. Overhauls are part of the maintenance program. Part 91 operators are not required to comply with a manufacturer’s entire maintenance program; as such, overhauls are not mandatory for part 91 operators.
As a purely Part 91 operator with an aircraft whose engines have exceeded the manufacturer’s recommended calendar TBO interval; however, may still have hundreds or potentially thousands of operating hours remaining until the manufacturer’s recommended hourly TBO interval is reached, does the statement above “…Part 91 operators are not required to comply with a manufacturer’s entire maintenance program; as such, overhauls are not mandatory for part 91 operators.” from your perspective give credence that a Part 91 operator may continue to operate the aircraft and its engines practically and legally?
This interpretation by a Part 91 operator has the potential to save that operator hundreds of thousands to well over one million dollars in engine overhaul costs, or be able to have that operator defer those overhaul costs to a future time.
If a Part 91 operator using the above interpretation uses its own internal maintenance personnel, and the decision is made by that owner to continue to operate its aircraft’s engines per the above FAA National Policy beyond the manufacturer’s recommended TBO interval, then this is straightforward; however, if that same Part 91 operator has its aircraft maintenance performed by a Part 145 repair station, could that operator be at risk by having that repair station contradict the position of the Part 91 operator, mandating overhauls are due citing only the manufacturer’s recommended engine TBO interval, and potentially not issue return to service logbook entry sign offs.
I’ve spoken with several sources including aircraft manufacturers, engine manufacturers, Part 145 repair stations, Part 91 operators and FAA FSDO personnel, and have received a broad spectrum of interpretations on this topic. I’d be interested in learning your perspective on this issue, especially from Part 91 operators and Part 145 repair stations.
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