AIRWORTHINESS DIRECTIVE

CAA-AD-033/2002

Date of issue: March 05, 2002

AIRCRAFT - ELECTRICAL RACK 90VU (ATA 92) - MODIFICATION

Applicability: ATR 72-101, -102, -201, -202, -211, -212 and -212A model aircraft on which ATR modification 1447 has been embodied and ATR modification 4840 has not been accomplished.

Effective date: April 18, 2002

Compliance: Required as indicated in DGAC AD 2002-091-066(B).

Remarks: The compliance of this AD must be recorded in Aircraft Logbook, where applicable the requirements of this AD must be integrated into Aircraft Technical Documentation. Address inquiries concerning this AD to: Civil Aviation Authority, Airworthiness Division, Ruzyne Airport, 160 08 Prague 6, Czech Republic, tel.: 420 2 33320922, fax: 420 2 20562270.

Ing. Pavel MATOUŠEK

Director of Airworthiness Division

CAA CZ

DGAC AD No.: 2002-091-066(B)

ATR

ATR 72 aircraft

Electrical rack 90VU-Wire bundle routing on 93, 94 and 95VU carbon shelves (ATA 92)

1. APPLICABILITY:

ATR 72-101, -102, -201, -202, -211, -212 and -212A model aircraft on which ATR modification 1447 has been embodied and ATR modification 4840 has not been accomplished.

2. REASONS:

This Airworthiness Directive (AD) is prompted by a recent event involving an ATR 42-500, where, after having left the parking with the RH engine, the crew tried to start without success the LH engine.

Investigations revealed that on electrical rack 90VU, a chafing had occurred between the carbon structure of the 95VU shelf and the main wire bundle. This chafing led to a short circuit, which caused burnt damage on several wires of the bundle (including LH engine ignition circuits) and on the protective sheath. It was determined that the chafing and subsequent electrical short circuit were most likely caused by a miss positioning of the bundle on the shelf during a maintenance action. This created a direct contact between the bundle and the carbon shelf (abrasive structure). This event is also possible on shelves 93VU and 94VU.

The following corrective actions mandated by this AD is intended to warrant a securely retain of the involved wire bundle in order to prevent a chafing which could cause a short circuit and potential loss of several functions.

3. COMPLIANCE:

The following measures are rendered mandatory on the effective date of this AD:

Before reaching 500 FH since the effective date of this AD and no later than September 01, 2002, install a fixing device between the wire bundles and the carbon shelves structure according to the instructions given in Service Bulletin ATR 72-92-1007.

REF.: Service Bulletin ATR 72-92-1007

Any later approved revision of this SB is acceptable.

EFFECTIVE DATE: MARCH 02, 2002