FAA InFO 24003, reminds part 135 operators that the passenger seating configuration of an aircraft can be altered to lower the seating count, but notes the seats must be physically removed. This type of physical removal often necessitates obtaining a Supplemental Type Certificate.
Applicability for many regulations is based upon the number of passenger seats installed in the aircraft. This includes the regulation specifying when a Flight Data Recorder (FDR) is required and the specific number of parameters that the FDR must capture (14 CFR 135.152).
The FDR regulation for part 135 specifies different requirements based upon the installed “passenger seating configuration” and other metrics. For turbine-powered aircraft with 10 to 30 seats (and manufactured after August 19, 2002) the FDR must record data for 88 parameters.
In the case of the FDR rule and other regulations, the requirements specified for part 135 operations are more stringent than the rules for the same aircraft when operated under part 91. Initial purchasers of an aircraft may have opted for equipment that meets the part 91 standard. If an air charter operator later wishes to use that aircraft in commercial operations, potentially extensive and expensive upgrades may be necessary to conform the aircraft to part 135 regulations or the aircraft may need to be reconfigured to lower the passenger seating count.
NATA encourages operators to verify their aircraft passenger seating capacities are properly approved and that their aircraft meet the applicable equipment requirements. When considering adding a new aircraft to the air carrier certificate, operators should thoroughly review the aircraft documentation to ensure the type of equipment installed and whether any seat removals were properly performed.
NATA recommends use of Advisory Circular 135-44 – Part 135 Operator Aircraft Configuration Inspection as an aid to evaluate aircraft conformity to part 135 requirements.