SAIB AIR-21-11

FAA Aviation Safety

SPECIAL AIRWORTHINESS

INFORMATION BULLETIN SUBJ: ROTORCRAFT SERVO SYSTEM (JASC 6730) SAIB: AIR-21-11 Date: July 22, 2021 This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin (SAIB) alerts owners and operators of Robinson Helicopter Company (Robinson) Model R66, Model R44, and R44 II helicopters with D212-1, D212-5, D212-6, hydraulic servos manufactured before April 2014.

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 Regulation (14 CFR) part 39.

Background

In October 2020, an operator of a Robinson R66 reported that the cyclic control had become stiff on final approach/landing. The stiffness only occurred in certain directions of cyclic travel resulting in some difficulty controlling the aircraft. There were no reported anomalies for the preceding two hours of flight or on prior flights. The operator returned the servo to Robinson facility for disassembly. Robinson found excessive internal wear of the servo components during examination.

Wear on the drive assembly could cause the link not to move the control valve into a fully open position, restricting fluid flow and causing sluggish (stiff feeling) control inputs.

Recommendations

We recommend that owners/operators of Robinson Model R44, R44 II, and Model R66, helicopters with hydraulic servos manufactured before April 2014 perform the pre-takeoff check identified in R44 Service Bulletin SB-109 dated 30 June 2021, and R66 Service Bulletin SB-39, dated 30 June 2021.

For Further Information Contact

Patrick Farina, Aerospace Engineer, Cabin Safety and Environmental Systems Branch, AIR-795, FAA, Los Angeles ACO, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; telephone

(562) 627-5344; fax (562) 627-5210.; email patrick.farina@faa.gov.

For Related Service Information Contact

Robinson Helicopter Company, 2901 Airport Drive, Torrance, CA 90505; telephone 310-539-0508;

fax 310-539-5198; or at https://www.robinsonheli.com.