Feb. 16, 2021

When the FAA became aware that some Part 25 aircraft operating under Part 135 didn’t comply with § 25.813(e) or an authorized exemption, it issued Notice 8900.549, which required principal maintenance inspectors to review the conformity of their Part 135 aircraft and enter the data in the FAA’s Safety Assurance System database.

It was a simple process: if the airplane has an interior door, confirm that it’s properly configured for Part 135 operations, if not, reconfigure it or remove the aircraft from Part 135 operations.

Review the notice.

Most Part 25 business aircraft have an exemption that allows for the installation of an interior door when operating under Part 91, said Michael P. McCullough, chair of NBAA’s Part 135 Issues subcommittee. “To operate for hire or common carriage under Part 135, those same aircraft must comply with the exemption limitations – a process that usually involves an approved maintenance function to remove or lock the door open.

“I think the confusion originated with Amendment 25-116, Miscellaneous Cabin Changes. In 2004, it changed § 25.813(e), from no door between passenger compartments to no door between the emergency exits and any passenger seat occupied for takeoff and landing,” McCullough added.

What iteration of § 25.813(e) applies depends on the airplane’s type certificate date, not its date of manufacture. “Airplanes with a certification basis prior to Amendment 25-116 are grandfathered in,” he said.

In either case, type certificates usually come with a number of exemptions and limitations, FAA-approved equivalent levels of safety, and supplemental type certificate modifications. They itemize the conformity of Part 25 aircraft for operations under Part 91 and Part 135, said McCullough. “In many cases, operators and inspectors were already complying with the notice, but some started looking into it more deeply than needed.”

While the FAA required inspectors to complete their assigned tasks by the first quarter of 2021, compliance is still an issue for any operator adding an aircraft to a Part 135 certificate, said McCullough. “If your airplane uses a door under an approved exemption, operators need to look at that exemption and comply with the associated requirements for 135 operations. This information is public and available on the FAA website.”

View the FAA website.