The FAA has issued Handbook Bulletin HBAW 04-06E in an attempt to clarify issues surrounding maintenance requirements under FAR Part 135. The bulletin has been amended to suspend its compliance time requirement because the FAA is considering a rulemaking effort to remove the words “type-certificated” (TC) from the language of FAR 135.411.

Historically the FAA has allowed Part 135 operators using aircraft TC’d for more than nine passenger seats to operate under the less stringent maintenance requirements of FAR 135.411(a)(1) provided the aircraft was actually configured for nine or fewer seats. Passenger seats are considered to be any seats in the aircraft that are not pilot seats and are certified to be used during takeoff and landing.

As a result, many operators either removed the extra seats or placarded them against use, then obtained a field approval authorization from the FAA to qualify for FAR 135.411(a)(1).

Recently, the FAA reversed its thinking and determined simple removal or placarding was insufficient and a supplemental type certificate (STC) would be necessary to avoid the more stringent FAR 135.411(a)(2) maintenance requirements.

Currently, according to regulations, reduction of the TC’d passenger seating configuration must be accomplished by changing the aircraft’s approved seating configuration. Doing so, in most cases, is a significant change to the type design that must be done in accordance with an STC or an amendment to the TC. In some instances, the removal of a seat in an aircraft may not constitute a major change.

If the aircraft type certificate data sheet permits a maximum number of passengers greater than the “nine or fewer” limit, the FAA requires either the manufacturer’s amendment to the TC, or an STC for an interior layout, to define an eligible seating configuration to qualify under FAR 135.411(a)(1). Reducing an aircraft’s seating capacity to qualify under FAR 135.411(a)(1) by any other method will not be acceptable.

Operators complained bitterly about the extreme cost of STC development, prompting David Cann, the FAA’s aircraft maintenance division manager, to comment at the NATA convention earlier this year, “It’s not our intention to make someone pay $50,000 for a piece of paper.”

According to an FAA spokesman, “Just putting a placard on a seat does not mean that the seat no longer exists. The aircraft is no less complex. Current regulations stipulate that the number of seats the aircraft was certified with is to be used as the determining factor of what kind of maintenance program the aircraft will be maintained under, not the number of seats that are in use on the aircraft. It is important to point out that this HBAW is a revision (revision “E”) which means that it isn’t new. Also, the regulation hasn’t changed and the HBAW doesn’t change the regulation. The HBAW is provided for information.”

If the FAA does remove “type-certificated” from the rule language it will allow operators to follow the FAR 135.411(a)(1) maintenance requirements based on the current approved configuration of the aircraft not just the TC’d configuration. However, it is important to note that the handbook contains many “what if” explanations and should be consulted by the operator.