The FAA is adopting a new airworthiness directive (AD) for various helicopters. This AD was prompted by a report of a loss of tail rotor authority due to auxiliary system fluid ...
[Docket No. FAA-2026-2297; Project Identifier AD-2025-00184-R; Amendment 39-23366; AD 2026-11-05]
RIN 2120-AA64
AGENCY:
Federal Aviation Administration (FAA), DOT.
ACTION:
Final rule.
SUMMARY:
The FAA is adopting a new airworthiness directive (AD) for various helicopters. This AD was prompted by a report of a loss of tail rotor authority due to auxiliary system fluid loss caused by a yaw pedal damper housing fatigue fracture and attachment bolt fatigue fracture. This AD requires performing repetitive visual inspections of the auxiliary servo assembly, a fluorescent penetrant inspection (FPI) of the yaw pedal damper housing and, if necessary, corrective actions. This AD also requires determining and recording the remaining life of a certain part and revising the existing rotorcraft flight manual (RFM) to provide the flight crew with procedures to follow under certain conditions. This AD also requires revising the airworthiness limitations section (ALS) of the existing maintenance manual (MM) or instructions for continued airworthiness (ICAs) and the existing approved maintenance or inspection program, as applicable by incorporating a new service life limit for a certain part. The FAA is issuing this AD to address the unsafe condition on these products.
DATES:
This AD is effective July 9, 2026.
The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of July 9, 2026.
ADDRESSES:
AD Docket:
You may examine the AD docket at
regulations.gov
under Docket No. FAA-2026-2297; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this final rule, any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Material Incorporated by Reference:
For Sikorsky Aircraft Corporation material identified in this AD, contact
( printed page 33591)
Sikorsky Field Representative or Sikorsky's Service Engineering Group at Sikorsky Aircraft Corporation, Mailstop K100, 124 Quarry Road, Trumbull, CT 06611; phone: 1-800-946-4337 (1-800-Winged-S); email:
wcs_cust_service_eng.gr-sik@lmco.com;
website:
sikorsky360.com.
You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 10101 Hillwood Parkway, Fort Worth, TX 76177. For information on the availability of this material at the FAA, call (817) 222-5110. It is also available atregulations.gov
under Docket No. FAA-2026-2297.
FOR FURTHER INFORMATION CONTACT:
Fatin Saumik, Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: (516) 228-7350; email:
ECB-COS@faa.gov.
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 various helicopters. The NPRM was published in the
Federal Register
on March 13, 2026 (91 FR 12314). The NPRM was prompted by a report of an accident involving a Sikorsky Aircraft Model S-61N helicopter due to the loss of tail rotor authority resulting from auxiliary system fluid loss. An investigation revealed that the auxiliary system fluid loss was caused by a yaw pedal damper housing fatigue fracture and attachment bolt fatigue fracture. During the investigation, it was identified that a non-conforming yaw pedal damper housing lug radius, improper maintenance (failure to properly torque and safety wire bolts), and improper operation (failure to heed the caution in the RFM regarding full activation of rudder pedals in less than five seconds) were contributing factors to the unsafe condition.
In the NPRM, the FAA proposed to require performing repetitive visual inspections of the auxiliary servo assembly, an FPI of the yaw pedal damper housing and, if necessary, corrective actions. The FAA also proposed to require determining and recording the remaining life of a certain part and revising the existing RFM to provide the flight crew with procedures to follow under certain conditions. Additionally, the FAA proposed to require revising the ALS of the existing MM or ICAs and the existing approved maintenance or inspection program, as applicable by incorporating a new service life limit for a certain part. The FAA is issuing this AD to detect and address cracking of the yaw pedal damper housing and attachment bolts and a non-conforming lug radius on the yaw pedal damper housing. The unsafe condition, if not addressed, could result in auxiliary system fluid loss, loss of tail rotor authority, and consequent reduced controllability of the helicopter or loss of control of the helicopter.
Discussion of Final Airworthiness Directive
Comments
The FAA received no comments on the NPRM or on the determination of the costs.
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, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Sikorsky Aircraft Corporation S-61 Helicopter Alert Service Bulletin ASB 61B65-25, Basic Issue, dated October 17, 2022, as corrected by Sikorsky Aircraft Corporation S-61 Helicopter Alert Service Bulletin Errata, effective February 3, 2026 (ASB 61B65-25, dated October 17, 2022). This material specifies procedures for repetitive visual inspections of the auxiliary servo assembly, an FPI of the yaw pedal damper housing and, if necessary, corrective actions to include removing from service the yaw pedal damper check valve housing and attachment bolts and replacement with airworthy parts. This material also includes procedures for determining and recording the remaining life of a certain part. This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the
ADDRESSES
section.
Costs of Compliance
The FAA estimates that this AD affects 76 helicopters of U.S. registry.
The FAA estimates the following costs to comply with this AD:
Estimated Costs
Action
Labor cost
Parts cost
Cost per
product
Cost on U.S.
operators
Visually inspect auxiliary servo assembly
1 work-hour × $85 per hour = $85
$0
$85
$6,460 per inspection cycle.
Determine remaining life of yaw pedal damper check valve housing
3 work-hours × 85 per hour = 255
0
255
19,380.
Inspect yaw pedal damper check valve housing and attachment bolts
15 work-hours × 85 per hour = 1,275
0
1,275
96,900.
Revise RFM
1 work-hour × 85 per hour = 85
0
85
6,460.
Revise ALS
1 work-hour × 85 per hour = 85
0
85
6,460.
Record life limit in existing helicopter log card
1 work-hour × 85 per hour = 85
0
85
6,460.
The FAA estimates the following costs to do any repairs or replacements that would be required based on the results of the inspection. The agency has no way of determining the number of helicopters that might need these repairs or replacements.
( printed page 33592)
On-Condition Costs
Action
Labor cost
Parts cost
Cost per
product
Blend repair and remeasure housing edge break radius
4 work-hours × $85 per hour = $340
$0
$340
Replace yaw pedal damper check valve housing
1 work-hour × 85 per hour = 85
1,200
1,285
Replace attachment bolts
1 work-hour × 85 per hour = 85
1 (per bolt)
86
FPI of yaw pedal damper check valve housing and attachment bolts
2 work-hours × 85 per hour = 170
0
170 per inspection cycle
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:
(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.
This AD was prompted by a report of a loss of tail rotor authority due to auxiliary system fluid loss caused by a yaw pedal damper housing fatigue fracture and attachment bolt fatigue fracture. The FAA is issuing this AD to detect and address cracking of the yaw pedal damper housing and attachment bolts and a non-conforming lug radius on the yaw pedal damper housing. The unsafe condition, if not addressed, could result in auxiliary system fluid loss, loss of tail rotor authority, and consequent reduced controllability of the helicopter or loss of control of the helicopter.
(f) Compliance
Comply with this AD within the compliance times specified, unless already done.
(g) Repetitive Visual Inspection and Corrective Actions
As of the effective date of this AD, before the first flight of each day, inspect the lockwire to determine if attachment hardware does not rotate under finger pressure, and use a high-powered light source and mirror to perform a visual inspection of the auxiliary servo assembly located in the controls compartment (also known as the broom closet) for hydraulic fluid leakage, cracks, missing or loose lockwire, and compromised bolt security (loose, missing, cracked, fractured, or stretched bolts) in accordance with the Accomplishment Instructions Section 3.C.(3)(a) and (b) of Sikorsky Aircraft Corporation S-61 Helicopter Alert Service Bulletin ASB 61B65-25, Basic Issue, dated October 17, 2022, as corrected by Sikorsky Aircraft Corporation S-61 Helicopter Alert Service Bulletin Errata, effective February 3, 2026 (Sikorsky ASB 61B65-25).
(1) If there is any hydraulic fluid leakage, compromised bolt security (loose, missing, cracked, fractured, or stretched bolts), or if there are any cracks on the yaw pedal damper check valve housing, before further flight, replace the yaw pedal damper check valve housing and the associated attachment bolts with serviceable parts.
(2) If there is any loose or missing lockwire, before further flight, inspect that each bolt has a torque value of 45-50 in./lbs. and perform the applicable corrective actions as follows.
(i) If the torque value is correct replace the lockwire.
(ii) If the torque value is below 45 in./lbs. or above 50 in./lbs., or if evidence of compromised bolt security (loose, missing, cracked, fractured, or stretched bolts) is found, replace the yaw pedal damper check valve housing, the associated attachment bolts, and lockwire with serviceable parts.
(h) Determining Life and Parts Replacement
Within 10 hours time-in-service (TIS) from the effective date of the AD:
(1) Determine the remaining life of the yaw pedal damper check valve housing having part number S6165-61517 in accordance with the Accomplishment Instructions, paragraph 3.B., of Sikorsky ASB 61B65-25
( printed page 33593)
and record it in the existing helicopter log card or equivalent record.
(2) Before the yaw pedal damper check valve housing has accumulated 30,000 total hours TIS or within 60 days after the effective date of this AD, whichever occurs later, remove the yaw pedal damper check valve housing from service and replace with a serviceable part.
(i) Fluorescent Penetrant Inspection (FPI) and Corrective Action
(1) Within 150 hours TIS or 4 months, whichever occurs first after the effective date of this AD, perform an FPI of the yaw pedal damper check valve housing in accordance with the Accomplishment Instructions, paragraphs 3.C.(3) through (9), of Sikorsky ASB 61B65-25. If there are any cracks in the yaw pedal damper check valve housing, before further flight, remove the yaw pedal damper check valve housing and the associated attachment bolts from service and replace the affected parts with serviceable parts. This FPI terminates the daily checks required by paragraph (g) of this AD.
(2) After accomplishing the actions as required by paragraph (i)(1) of this AD, thereafter at every 15 hours TIS, perform the repetitive visual inspection required by paragraph (g) of this AD.
Note 1 to paragraph (i)(2):
The 15-hour repetitive inspection is established to coincide with any existing 15-hour TIS safety inspections of the auxiliary servo assembly. For example, Sikorsky Aircraft Model S-61N helicopters have this inspection as specified in Sikorsky Aircraft S-61 Equalized Inspection and Maintenance Program, SA 4047-13, Revision No. 18, dated January 15, 2014.
(j) Update Maintenance Records
Within 30 days after the effective date of this AD, incorporate into existing maintenance records required by 14 CFR 91.417(a)(2) or 135.439(a)(2), as applicable for your helicopter, a new service life limit of 30,000 hours TIS for the yaw pedal damper check valve housing.
(k) Provisions for Alternative Actions and Intervals
After the action required by paragraph (j) of this AD has been accomplished, no alternative actions and associated thresholds and intervals, including life limits, are allowed.
(l) Revision of Existing Rotorcraft Flight Manual (RFM)
Within 30 days after the effective date of this AD, revise the normal procedures section, specifically the preflight inspection of the flight control servo system procedure, of the existing RFM for the helicopter by inserting the information specified in figure 1 to paragraph (l) of this AD or by inserting a copy of this AD.
Figure 1 to Paragraph (l)—New RFM Caution
(m) No Reporting or Returning Parts Requirements
Although Sikorsky ASB 61B65-25 specifies submitting certain information or returning an affected part to the manufacturer, this AD does not include those requirements.
(n) Special Flight Permits
Special flight permits are prohibited.
(o) Alternative Methods of Compliance (AMOCs)
(1) The Manager, East Certification Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the East Certification Branch, send it to the attention of the person identified in paragraph (p) of this AD and email to:
AMOC@faa.gov.
(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.
(p) Additional Information
(1) For more information about this AD, contact Fatin Saumik, Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: (516) 228-7350; email:
ECB-COS@faa.gov.
(2) Sikorsky Aircraft Corporation material identified in this AD that is not incorporated by reference is available at the address specified in paragraph (q)(3) of this AD.
(q) Material Incorporated by Reference
(1) The Director of the Federal Register approved the incorporation by reference of the material listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this material as applicable to do the actions required by this AD, unless the AD specifies otherwise.
(i) Sikorsky Aircraft Corporation S-61 Helicopter Alert Service Bulletin ASB 61B65-25, Basic Issue, dated October 17, 2022, as corrected by Sikorsky Aircraft Corporation S-61 Helicopter Alert Service Bulletin Errata, effective February 3, 2026.
(ii) [Reserved]
(3) For Sikorsky Aircraft Corporation material identified in this AD, contact Sikorsky Field Representative or Sikorsky's Service Engineering Group at Sikorsky Aircraft Corporation, Mailstop K100, 124 Quarry Road, Trumbull, CT 06611; phone: 1-800-946-4337 (1-800-Winged-S); email:
wcs_cust_service_eng.gr-sik@lmco.com;
website: sikorsky360.com.
(4) You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 10101 Hillwood Parkway, Fort Worth, TX 76177. For information on the availability of this material at the FAA, call (817) 222-5110.
