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FAASTeam Notice
Type: Local Air Safety Information
Notice Date: Friday, July 5, 2019
Notice Number: NOTC9555
Airworthiness Bulletin - Flight Control Cable Terminals
This notice expired on
Monday, August 5, 2019

 

Introduction

This Special Airworthiness Information Bulletin CE-19-13 alerts owners, operators, maintenance technicians, and inspectors of an airworthiness concern, specifically cracking and fracturing of flight control cable terminal attachment fittings connected to turnbuckle barrels on all 14 CFR part 23 and CAR part 3 airplanes with mechanical flight control cables.

With the exception of AD 2013-02-13, which addresses specific turnbuckle connections in the stabilator control system on certain Piper Aircraft Inc. airplane 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. However, the FAA continues to monitor this concern, and may take additional action based on data received from operators and/or further examination.

Background

Turnbuckle connections are widely used in flight control systems on a multitude of airplane models that utilize mechanical flight control cables. The FAA has, over the years, received numerous reports of failures of the cable/turnbuckle attachment fittings, which have caused or have the potential to cause loss of flight control in one axis. In many cases, the failures have been discovered during inspection or ground operations. For those that occurred in flight, the pilot was often able to land the airplane without damage, although this can be very challenging. Accidents with substantial damage have occurred in some cases.

The specific focus of this SAIB is on the connecting fittings that are attached (swaged) to the flight control cables and threaded onto the turnbuckles. These fittings are typically manufactured from a type of stainless steel that is susceptible to stress corrosion cracking under certain conditions over time. Based on multiple part examinations, the stress corrosion cracking originates at general corrosion pits on the surface of the parts. Because the cracks are primarily below the surface, they can be extremely difficult to detect. Because stress corrosion cracking is usually preceded by or with visible corrosion, any presence of even light or moderate corrosion on these fittings is cause for concern.

For further details, please see attached Special Airworthiness Information Bulletin: https://www.faasafety.gov/files/notices/2019/Jul/CE-19-13.pdf


For Further Information Contact: David Hirt, Aerospace Engineer, 901 Locust,                                      Phone: (816) 329-4050; fax:(816) 329-4090; e-mail: david.hirt@faa.gov.