Because of great strides in aviation technology, the FAA has issued a final rule that will require function-and-reliability (F&R) flight testing for all turbine-powered airplanes weighing 6,000 pounds or less, beginning on December 19.
Currently, function-and-reliability flight testing is required only for Part 23 certified airplanes that have a maximum certified weight of more than 6,000 pounds. But the FAA said that because of advancements in airplane structures, propulsion methods and systems technologies, the 6,000-pound demarcation is no longer justified.
After reviewing several recent proposed type certification (TC) projects for small jet-powered airplanes expected to weigh 6,000 pounds or less, the FAA determined that most, if not all, of these airplane designs will benefit from the F&R flight testing requirement.
The FAA acknowledged that type certification experience with the new very light jets (VLJ) led it to reconsider the existing exclusion of airplanes weighing 6,000 pounds or less. “This reconsideration was driven in part by difficulties encountered with the voluntary application of the requirement during the FAA type certification of [Eclipse Aviation’s] EA-500 VLJ and the subsequent problems experienced during that airplane’s entry into service,” the agency wrote.
The FAA assembled a team of technical staff to conduct a Special Certification Review (SCR) of the EA-500 certification program. That team’s report reviewed the FAA’s TC program and focused on four service problems encountered during the EA500’s entry into service (EIS).
The SCR team also reviewed Service Difficulty Report experience concerning airplane system deficiencies and malfunctions encountered after the EIS. The team developed eight findings and six recommendations.
Technologically Advanced Small Aircraft
According to the FAA, the technological advancements in new airplane designs and their high-performance potential prompted the agency to publish a notice of proposed rulemaking (NPRM) last year in which the agency proposed changes to the applicability of F&R flight testing procedures for Part 23 airplanes.
“In general, we proposed to expand the applicability of F&R flight testing requirements to all Part 23 turbine-powered airplanes that weigh 6,000 pounds or less to be certified under Part 23,” the FAA said. However, the exception will remain for gliders and piston-powered airplanes weighing 6,000 pounds or less that are type certified under Part 23.
The FAA said that the original decision to exclude certain airplanes weighing 6,000 pounds or less from F&R flight testing was based on the state of technology existing in 1950.
At that time, airplanes weighing 6,000 pounds or less were expected to be used mainly as personal airplanes. Such civil airplanes developed between 1945 and 1955 were typically piston singles with less than 300 hp and weighing 3,000 pounds or less.
The FAA said that technological advancements now allow airplanes that are 6,000 pounds or less to be more complex and automated than some transport-category airplanes of the 1960s and earlier.
Function-and-reliability flight testing simulates typical in-service flight operations for a new aircraft design. This flight testing is done before the aircraft’s final design approval leading to the issuance of a type certificate.
One of the SCR findings noted that the newly designed VLJs have modern and integrated complex avionics. Thus, the traditional approach of defining certification requirements based solely on weight is no longer valid.