EASA AD No: 2012-0040 

EASA Form 110 Page 1/2 

EASA AIRWORTHINESS DIRECTIVE 

AD No.: 2012-0040 

Date: 13 March 2012 

Note: This Airworthiness Directive (AD) is issued by EASA, acting in accordance with Regulation 

(EC) No 216/2008 on behalf of the European Community, its Member States and of the 

European third countries that participate in the activities of EASA under Article 66 of that 

Regulation. 

This AD is issued in accordance with EC 1702/2003, Part 21A.3B. In accordance with EC 2042/2003 Annex I, Part M.A.301, the 

continuing airworthiness of an aircraft shall be ensured by accomplishing any applicable ADs. Consequently, no person may operate an 

aircraft to which an AD applies, except in accordance with the requirements of that AD, unless otherwise specified by the Agency [EC 

2042/2003 Annex I, Part M.A.303] or agreed with the Authority of the State of Registry [EC 216/2008, Article 14(4) exemption]. 

Type Approval Holder’s Name : 

BAE SYSTEMS (OPERATIONS) LTD 

Type/Model designation(s) : 

BAe 146 and AVRO 146-RJ aeroplanes 

TCDS Number: EASA.A.182 

Foreign AD: Not applicable 

Supersedure: None 

ATA 24 Electrical Power – Ceramic Terminal Blocks – Inspection / 

Replacement 

Manufacturer(s): BAE Systems (Operations) Ltd, British Aerospace plc, British Aerospace 

(Commercial Aircraft) Ltd, British Aerospace (Operations) Ltd, British Aerospace 

Regional Aircraft Ltd, British Aerospace Regional Aircraft trading as Avro 

International Aerospace. 

Applicability: BAe 146 and AVRO 146-RJ series aeroplanes, all models, all serial numbers. 

Reason: Moisture ingress has been discovered on certain ceramic terminal blocks, 

mounted on the engine cowlings, through which the wiring for the engine fire 

extinguishers, fire detection circuits and engine and intake anti ice system are 

routed. The affected terminal blocks were introduced through BAE Systems SB 

71-077-01693A (modification HCM01693A) during the period 2002-2004, as this 

modification was mandated by CAA UK AD 005-10-2001. Moisture ingress has 

a detrimental effect on the insulation resistance of the ceramic terminal block 

with the resultant possibility of interconnections between all terminals. Most of 

the possible failure conditions in the terminal block should result in an evident 

warning or other indication. However, the functional loss of the number 2 fire 

bottle would be a dormant failure. 

This condition, if not corrected, could result in the failure of a fire bottle to 

discharge when activated, possibly preventing the flight crew in extinguishing an 

engine fire. 

For the reasons described above, this AD requires a one-time inspection of the 

ceramic terminal blocks to determine the insulation resistance and, depending 

on findings, replacement of terminal blocks, and the reporting of the results to 

the BAE Systems. These will be used to establish a suitable repetitive 

inspection interval, which is expected to be introduced through the Maintenance 

Review Board (MRB) process. 
EASA AD No: 2012-0040 

EASA Form 110 Page 2/2 

Effective Date: 27 March 2012 

Required Action(s) 

and Compliance 

Time(s): 

Required as indicated, unless accomplished previously: 

(1) Within 4 000 flight cycles or 18 months, whichever occurs first after the 

effective date of this AD, conduct an insulation resistance test on each 

terminal block in accordance with the accomplishment instructions, 

paragraphs 2.C, 2.D, 2.E and 2.F, of BAE Systems (Operations) Ltd 

Inspection Service Bulletin (ISB) 24-143 (the ISB).

(2) If, during the inspection as required by paragraph (1) of this AD, any 

defective terminal block is identified, before next flight, replace it with a 

serviceable terminal block. 

(3) Within 30 days after the inspection as required by paragraph (1) of this AD, 

complete the test result sheets in Appendices 1, 2, 3 and 4 and the 

inspection report in Appendix 6 of the ISB and send this to BAE Systems 

(Operations) Ltd in accordance with the instructions of paragraph 2.I of the 

ISB. 

Ref. Publications: BAE Systems (Operations) Limited ISB.24-143 dated 26 September 2011. 

The use of later approved revisions of this document is acceptable for 

compliance with the requirements of this AD. 

Remarks : 1. If requested and appropriately substantiated, EASA can approve Alternative 

Methods of Compliance for this AD. 

2. This AD was posted on 07 February 2012 as PAD 12-008 for consultation 

until 06 March 2012. No comments were received during the consultation 

period. 

3. Enquiries regarding this AD should be referred to the Safety Information 

Section, Executive Directorate, EASA. E-mail ADs@easa.europa.eu. 

4. For any question concerning the technical content of the requirements in 

this AD, please contact: 

BAE Systems (Operations) Ltd, Customer Information Department, 

Prestwick International Airport, Ayrshire, KA9 2RW, Scotland, The United 

Kingdom; Telephone +44 1292 675207, Facsimile +44 1292 675704; 

E-mail: RApublications@baesystems.com.