Airworthiness Directives: Hamilton Sundstrand Corporation Propellers

Airworthiness Directives; Hamilton Sundstrand Corporation Propellers

Supplementary Information

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all Hamilton Sundstrand Corporation (Hamilton Sundstrand) Model 14SF-7, 14SF-15, and 14SF-23 propellers. The NPRM published in the Federal Register on September 7, 2023 (88 FR 61480). The NPRM was prompted by a report of an auxiliary motor and pump installed on a non-Hamilton Sundstrand propeller failing to feather the propeller in flight through either the primary or the backup means. The failure was caused by motor magnets in the auxiliary motor and pump that were de-bonded due to corrosion at the magnet and housing interface. The de-bonded motor magnets prevented motor rotation. Hamilton Sundstrand Model 14SF-7, 14SF-15, and 14SF-23 propellers use the same auxiliary motor and pump. These propellers are installed on, but not limited to, De Havilland Aircraft of Canada Limited (Type Certificate previously held by Bombardier Inc.) Model DHC-8-100 series, DHC-8-200 series, and DHC-8-300 series airplanes. This condition, if not addressed, could result in reduced controllability of the aircraft and consequent loss of control of the aircraft.

In the NPRM, the FAA proposed to require the removal from service of an auxiliary motor and pump having part number (P/N) 782655-3 (Aerocontrolex P/N 4122-006009) and replacement with an auxiliary motor and pump having P/N 782655-4 (Aerocontrolex P/N 4122-056000). In the NPRM, the FAA also proposed to prohibit the installation of an auxiliary motor and pump having P/N 782655-3 (Aerocontrolex P/N 4122-006009) on any propeller. The FAA is issuing this AD to address the unsafe condition on these products.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from three commenters. The commenters were Collins Aerospace, Sierra Nevada Corporation, and an individual. Sierra Nevada Corporation noted that the AD does not apply to its fleet and had no objection to the NPRM. Two commenters, Collins Aerospace and an individual, recommended certain changes. The following presents the comments received on the NPRM and the FAA's response.

Request To Clarify the Use of "Any Propeller" in the NPRM

Two commenters, Collins Aerospace and an individual, observed that the use of the phrase "any propeller" in the NPRM causes confusion. The commenters noted that the phrase "any propeller" appears three times in the subject NPRM. Collins Aerospace stated that this use of "any propeller" language has caused some confusion related to AD 2023-16-06 [Amendment 39-22525 (88 FR 63513, September 15, 2023)]. An individual also observed that the use of the word "also" in the sentence, "This AD also prohibits installation of a certain auxiliary motor and pump on any propeller," in the Summary section of the proposed rule indicates or implies the prohibition is for other propellers in addition to what is identified in the applicability. The commenters requested that the FAA remove the phrase "any propeller" from all preamble and regulatory text regarding an installation prohibition in the AD. The commenters also requested that the FAA write the prohibition to show that it only pertains to the propeller models listed in this AD.

The FAA agrees to clarify regarding the use of the phrase "any propeller" and whether the prohibition only applies to the propeller models list in the AD. For clarification, all of the requirements of an AD can apply only to the propellers listed in the applicability. To eliminate any confusion, however, the FAA revised paragraph (h) of this final rule, Installation Prohibition, to specify that the installation prohibition applies to any propeller identified in paragraph (c) of this AD.

Conclusion

The FAA reviewed the relevant data, considered any comments received, and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these products. Except for minor editorial changes, and any other changes described previously, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Hamilton Sundstrand Service Bulletin (SB) 14SF-61-168, Revision 1, dated December 21, 2016. This service information specifies instructions for replacing the auxiliary motor and pump. Hamilton Sundstrand Corporation is a UTC Aerospace Systems Company. This service information is identified as both Hamilton Sundstrand Corporation and UTC Aerospace Systems. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in ADDRESSES .

Costs of Compliance

The FAA estimates that this AD affects 180 propellers installed on airplanes of U.S. registry.

The FAA estimates the following costs to comply with this AD:

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.

The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

This AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify that this AD:

(1) Is not a "significant regulatory action" under Executive Order 12866,

(2) Will not affect intrastate aviation in Alaska, and

(3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

The Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:

Part 39 Airworthiness Directives