This week you can look forward to five new features of the FAA’s recent rule changes that alter the small airplane rules, but have some minor effects on all other aircraft as well.
The new Part 23 rules become effective on Wednesday, August 30, 2017. All PMA applications subject to Part 23 and submitted on or after that date should ensure that they show compliance to the proper regulations. Your certification basis might be a prior revision level of Part 23, but as time marches on more and more projects will fall within the new Part 23 rules.
In some cases, the new Part 23 rules may make some significant changes.
One example is found in the changes involving instruments. The old rules required an airspeed indicator, an altimeter, a magnetic direction indicator, and a speed warning device for turbine engine powered airplanes. 14 C.F.R. § 23.1303 (2011). The new corollary rule does not require any specific flight instrument – instead it requires:
Sec. 23.2615 Flight, navigation, and powerplant instruments.
(a) Installed systems must provide the flightcrew member who sets or monitors parameters for the flight, navigation, and powerplant, the information necessary to do so during each phase of flight. This information must–
(1) Be presented in a manner that the crewmember can monitor the parameter and determine trends, as needed, to operate the airplane; and
(2) Include limitations, unless the limitation cannot be exceeded in all intended operations.
(b) Indication systems that integrate the display of flight or powerplant parameters to operate the airplane or are required by the operating rules of this chapter must–
(1) Not inhibit the primary display of flight or powerplant parameters needed by any flightcrew member in any normal mode of operation; and
(2) In combination with other systems, be designed and installed so information essential for continued safe flight and landing will be available to the flightcrew in a timely manner after any single failure or probable combination of failures.
This new language leaves it up to the designer to identify the parameters for the flight that the flight crew must set or monitor. This potentially undermines other related regulations, though. For example, the instructions for continued airworthiness regulations require the design approval holder to publish instructions “for each appliance required by this chapter” [meaning the FAA’s safety regulations]. Under the old regulations, it was clear that the instructions for the airspeed indicator, the altimeter, and the magnetic direction indicator were required to be part of the instructions for continued airworthiness. Under the new regulations, this linkage is less plain, and will likely lead to a need for additional FAA guidance.
On the other hand, the new performance-oriented standard may allow PMA applicants greater freedom in designing new improvements to instruments in order to give the flight crew greater information and greater control over the information.