A recent FAA airworthiness handbook bulletin that aims to clarify the maintenance requirements for Part 135 aircraft might not be a good thing for some operators, but it might prove beneficial for some maintenance facilities.

The bulletin–HBAW 04-06 to Handbook 8300.10–declares that Part 135 aircraft must be maintained according to the number of passenger seats listed on the type certificate rather than the number of seats an operator makes available for use. The FAA said it issued the bulletin to its inspectors to prevent inconsistencies among FSDOs, but some operators argue it is “rulemaking by handbook bulletin.”

The bulletin reiterates that Part 135 aircraft certified for at least 10 seats must adhere to more stringent maintenance and operational standards than those with nine or fewer seats. Some operators had been meeting the nine or fewer standard by simply cordoning off seats or placarding them as unusable.