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A commenter noted that the FAA has historically not applied the classification of “critical part” in FAA airworthiness standards and asked for clarification. The use of critical parts is consistent with the FAA’s certification approach for electric engines and is necessary for an acceptable level of safety. One commenter questioned whether the requirements of EASA Special Condition E-19 EHPS.80, which accounts for the complete inability to isolate components that could cause a hazard to aircraft, should be added to the airworthiness criteria for the Model M001. propeller accounting The FAA does not agree, as the requirement to isolate components that could cause a hazard to the aircraft is in EHPS.350(d), EHPS Control System, not in EHPS.80. The requirement in EHPS.350 raised by the commenter is addressed by AM1.2710 Engine Control Systems, AM1.2717 Safety Analysis, and AM1.2733 Engine Electrical Systems. Since the Archer M001 is a special class aircraft and the engines will be approved with the aircraft, the means by which components prevent a hazard from developing may be implemented either at the engine-level or at the aircraft-level.

Aircraft-Level Requirements

propeller accounting

One such instance was identified in AM1.2135(a), where the criteria referenced an “operating envelope.” The FAA’s intent was not to imply this flight envelope was different from others referenced in these airworthiness criteria. To be consistent, the FAA has generally replaced ”operating envelope” with “approved flight envelope” where applicable such as AM1.2105(f) and AM1.2135(a), except for AM1.2425(b) and AM1.2710(d), where the proposed requirements define operating envelopes specific to the engine. Additionally, the FAA included AM1.2135(a)(7) to incorporate the steepest approach gradient within the approved flight envelope. Another commenter requested the FAA clarify whether § 33.29(f) applies to the Model M001. Section 33.29(f) requires a safety assessment of incorrect fit of instruments, sensors, or connectors, and references a § 33.75 turbine engine safety analysis that is not applicable to the Archer M001 electric engines.

AM1.2712 Stress Analysis

Proposed AM1.2717(c) contained requirements for how the applicant must comply with § 33.75(e). The FAA has modified proposed AM1.2717(c) to reference the ICA in AM1.1529 for compliance with § 33.75(e)(1). During the review of this comment, it was determined that § 33.75(a)(1) should be included in AM1.2717(a) and the applicability of AM1.2717(b) should be clarified using information from the existing standard § 33.75(c). Several commenters noted inconsistent utilization of the term “flight envelope” and requested clarification.

propeller accounting

§ 33.23 Engine Mounting Attachments and Structure

The FAA received and reviewed comments from EASA, Overair, and TCCA requesting the FAA revise, remove, and clarify proposed airworthiness criteria related to HIRF exposure. Multiple commenters requested that the FAA align AM1.2240(c) with EASA SC-VTOL.2240(d). The FAA notes that AM1.2240(c) is similar to SC-VTOL.2240(d), although SC-VTOL.2240(d) refers to “lift/thrust unit” instead of “engine.” The EASA term “lift/thrust unit” includes the engine and propeller or rotor assembly. For the Model M001, other rotating parts within the system, except for propeller blades or rotors, should be evaluated using typical rotor burst methods, including shielding where practical. One commenter recommended the FAA revise proposed AM1.2225 to be more generic by specifying source of loads for any relevant structural components, and not only the components specific to the Model M001. The FAA disagrees, as these airworthiness criteria are specific to the applicant’s design.

  • The bird ingestion requirements in AM1.2718 are not driven by either of these bird sizes.
  • The FAA did not find the recommended language appropriate for AM1.2709 and did not make any changes to AM1.2709.
  • The FAA proposed criteria that created new or modified definitions for the Model M001 powered-lift.
  • (c) The applicant must submit to the FAA a program to show how changes to the ICA made by the applicant or by the manufacturers of propeller parts will be distributed, if applicable.
  • (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.
  • The FAA received requests to remove proposed AM1.2165(b) since the Model M001 powered-lift is not seeking FIKI approval.

AM1.2335 Lightning and Static Electricity Protection

  • (1) The engine electrical-power distribution system must be designed to provide the safe transfer of electrical energy throughout the electrical power plant.
  • The FAA also received a request to revise AM1.2110 to require minimum safe speed for “each flight condition and configuration” instead of only for each flight condition.
  • Propeller Industries is not licensed by the state of California and the accounting services being offered do not require a state license.
  • The FAA added a more prescriptive requirement specifically for control margin awareness in response to these recommendations.
  • The critical part requirements are integral for creating a propeller with an equivalent level of safety and are retained for the Model M001.
  • (iii) Multiple failures referred to in paragraph (d) of this section, or that result in the hazardous propeller effects defined in paragraph (g)(1) of this section.

The relatively low revolution speed and resulting low centrifugal acceleration effect on ice shedding capability, as well as the effect of increased torque on electric engines, need to be addressed in an inadvertent icing encounter. (a) The aircraft must maintain lateral and directional trim without further force upon, or movement of, the primary flight controls or corresponding trim controls by the pilot, or the flight control system, under all normal operations while using applicable sources of lift. (b) For aircraft approved for essential performance, the applicant must determine the takeoff performance to 50 feet above the takeoff surface such that a rejected takeoff resulting in safe stop or landing can be made at any point along the takeoff flight path following a critical change of thrust.

AM1.2200 Structural Design Envelope

A critical change of thrust will require a dedicated assessment encompassing all the above elements. The FAA acknowledges the risk posed by these hazards but does not agree that additional specific requirements are necessary. Further, commenters suggested that determining the rate of hazardous propeller effects should be less ambiguous. The FAA does not concur with the suggestion that the acceptable hazardous propeller failure rate is too high. The criteria are derived from part 35 requirements, which provide an acceptable level of safety for both part 23 and 25 airplanes. The FAA does not concur with the suggestion that propeller release and unbalance should be treated as catastrophic and not hazardous effects.

Additional Changes Made to the Proposed Criteria

(a) The applicant must comply with § 33.75(a)(1) and (2) using the failure definitions in paragraph (d) of this section. (a) In addition, as part of the system safety assessment of AM1.2710(g) and AM1.2733(h), the applicant must assess the possibility and subsequent effect of incorrect fit of instruments, sensors, or connectors. Where practicable, the applicant must take design precautions to prevent incorrect configuration of the system. Environmental limits that cannot be adequately substantiated by endurance demonstration, validated analysis, or a combination thereof must be demonstrated by the system and component tests in AM1.2727.

Another airline scare in Australian as regional jet makes emergency landing – Business Standard

Another airline scare in Australian as regional jet makes emergency landing.

Posted: Thu, 23 Mar 2017 07:00:00 GMT [source]

AM1.2110 Minimum Safe Speed

  • The FAA received multiple comments asking to define or qualify what would be an acceptable margin for purposes of proposed AM1.2730(a) and whether a rotor burst analysis is required at the aircraft level.
  • (ii) A significant thrust in the opposite direction to that commanded by the pilot.
  • The FAA is charged under § 21.17(b) to provide an equivalent level of safety to the existing airworthiness standards.
  • The requirement in EHPS.350 raised by the commenter is addressed by AM1.2710 Engine Control Systems, AM1.2717 Safety Analysis, and AM1.2733 Engine Electrical Systems.
  • The FAA agrees and did not adopt the qualifier “due to unintended temperature influences” in these final airworthiness criteria.
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