Sensor lock-wire

SW-07-10 November 06, 2006 http://www.faa.gov/aircraft/safety/alerts/SAIB This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin alerts you, owners and operators of Eurocopter France Models EC 155B and EC155B1 helicopters, to follow certain instructions during each pre-starting checklist.

Background

The European Aviation Safety Agency (EASA) published Airworthiness Directive (AD) 2006- 0214, dated July 14, 2006, in response to Eurocopter’s discovery that the electrical ground of the main gear box (MGB) oil pressure sensor is not accomplished via a dedicated sensor electrical connection, but instead via a sensor lock-wire. The consequence of this sensor lock-wire connection is that, in case of rupture or different positioning of the lock-wire, the MGB caution light cannot illuminate to warn of an MGB oil pressure drop. This could lead to prolonged flight with low MGB oil pressure and subsequent failure of the MGB. Recommendations

During each accomplishment of the pre-start checklist instructions, you should follow the instructions regarding the Caution Advisory Display (CAD) defined in section 4.3, paragraph 1 of the referenced EC 155 Flight Manuals. These CAD instructions are intended to detect a faulty MGB caution light.

EC 155 Aircraft Models Flight Manual Revision No. EASA Approval Date B 13 March 6, 2006 B1 7 March 6, 2006

In addition, you should report any instances where you find the MGB oil pressure caution light to be faulty as a result of a compromised sensor lock-wire. Please send this information to the contact below.

For Further Information Contact

Ed Cuevas, Aviation Safety Engineer, FAA Safety Management Group, ASW-112, 2601 Meacham Blvd., Fort Worth, Texas, 76137; phone: (817) 222-5355; e-mail: [email protected].

For Flight Manual Information Contact

American Eurocopter Corporation, 2701 Forum Drive, Grand Prairie, Texas 75053-4005, telephone (972) 641-3460, fax (972) 641-3527