Landing Gear Dampers Inspection

1 FAA Aviation Safety SPECIAL AIRWORTHINESS INFORMATION BULLETIN SUBJ: Landing Gear Dampers Inspection SAIB: SW-17-29 Date: October 10, 2017 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin alerts you, owners, operators, and certificated repairs facilities of Sikorsky 269C and C-1, 269D and 269D Configuration “A” model rotorcraft, of Alert Service Bulletins (ASBs) issued by Sikorsky Aircraft Corporation that recommend a one-time Load/Stroke Test (LST) of the landing gear dampers to be performed at an overhaul or repair facility. Improper servicing of these dampers, or their deterioration due to aging and normal wear, may lead to severe vibration on the ground (ground resonance), and coupled with improper pilot action to alleviate the condition, could possibly result in total loss of the rotorcraft. These LST requirements were subsequently incorporated into the current Helicopter Basic Handbook of Maintenance Instructions (HMI) for these rotorcraft models.

At this time, the airworthiness concern is not an unsafe condition that would warrant airworthiness directive (AD) action under Title 14 of the Code of Federal Regulations (14 CFR) part 39.

Background

The particular 269 models listed above incorporate landing gear dampers designed to alleviate ground resonance. However, these dampers, if not maintained with the correct charge pressures, have been attributed to incidents of ground resonance which resulted in major structural damage or total loss of the rotorcraft. Therefore, Sikorsky issued the following ASBs to ensure they must pass a one-time LST. The HMI’s were later revised to include the LST anytime the landing gear damper is serviced or overhauled.

Alert Service Bulletin

Date Model

ASB B-304

04/15/2014 S269C ASB C1B-041

04/15/2014 S269C-1 ASB DB-056

04/15/2014 S269D and S269D Configuration “A”

Recommendations

With the above information, supported by the statistical analyses of recent accidents, we recommend the following:

A one-time landing gear damper LST for the affected 269 models in compliance with the ASBs to improve protection against ground resonance accidents, unless the landing gear damper has been successfully serviced after April 15, 2014, either to the aforementioned ASB, or the updated HMI

2 requirements. Furthermore, whenever a landing gear damper is removed for maintenance, a successful LST as specified in the HMI is recommended.

- Perform the landing gear damper Load/Stroke Inspection requirements for SIKORSKY MODEL 269C per the latest Basic Handbook of Maintenance Instructions, Publication No. CSP-C-2, Appendix C, Section 5. - Perform the landing gear damper Load/Stroke Inspection requirements for SIKORSKY MODEL 269C-1 per the latest Basic Handbook of Maintenance Instructions, Publication No. CSP-C1-2, Appendix C, Section 5. - Perform the landing gear damper Load/Stroke Inspection requirements for SIKORSKY MODEL 269D per the latest Basic Handbook of Maintenance Instructions, Publication No. CSP-D-2, Appendix C, Section 5. - Perform the landing gear damper Load/Stroke Inspection requirements for SIKORSKY MODEL 269D Configuration “A” per the latest Basic Handbook of Maintenance Instructions, Publication No. CSP-D-9, Appendix C, Section 5.

For Further Information Contact

Neil Doh, Aerospace Engineer, FAA, Rotorcraft Certification Service, Boston Aviation Safety Section; 1200 District Avenue, Burlington, MA 01803; phone: (781) 238-7757; fax: (781) 238-0199; e-mail: [email protected].

For Related Service Information Contact

Sikorsky Rotorcraft Corporation; Commercial Systems and Services; Mailstop K100, 124 Quarry Road, Trumbull, CT 06611; Attention: Product Safety Manager; fax: (817) 762-6715; email: [email protected]