EASA AD No : 2011-0149R1 

EASA Form 110 Page 1/2 

EASA AIRWORTHINESS DIRECTIVE 

AD No.: 2011-0149R1 

Date: 23 September 2011 

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 : 

Eurocopter Deutschland GmbH 

Type/Model designation(s) : 

MBB-BK117 C-2 helicopters 

TCDS Number : EASA.R.010 

Foreign AD : not applicable 

Revision: This AD revises EASA AD 2011-0149 dated 05 August 2011. 

ATA 24 Electrical Power – Generator Control Unit – Identification / 

Replacement 

Manufacturer(s): Eurocopter Deutschland GmbH (ECD), American Eurocopter LLC 

Applicability: MBB-BK117 C-2 helicopters, all serial numbers. 

Reason: During an acceptance test procedure of a generator control unit (GCU), a 

short circuit occurred within the unit. 

The results of the subsequent investigation determined that a manufacturing 

discrepancy was the cause of this internal short circuit. All Part Number 

(P/N) P/N 51530-021EI “no MOD”, “MOD A” and “MOD B” GCU’s are 

potentially affected by this discrepancy. 

This condition, if not corrected, can lead to the loss of electrical generating 

power, possibly resulting in loss of relevant systems that are necessary for a 

safe continuation of the flight. 

To address this potential unsafe condition, EASA issued AD 2011-0149 to 

require the identification of each affected GCU and replacement with a 

serviceable unit. 

Since that AD was issued, ECD has demonstrated that, for helicopters that 

have already been modified in accordance with ECD Alert Service Bulletin 

(ASB) MBB BK117 C-2-24A-008 Revision 1, as required by § (3) of EASA 

AD 2011-0162, the risk of losing electrical generating power as addressed by 

this AD is much lower. 

For the reasons described above, this AD is revised, allowing an extended 

compliance time for the replacement of the affected GCU for helicopters that 

have already been modified in accordance with ECD ASB MBB BK117 C-2-

24A-008 Revision 1. 
EASA AD No : 2011-0149R1 

EASA Form 110 Page 2/2 

Effective Date: Revision 1: 30 September 2011 

Original issue: 19 August 2011 

Required Action(s) 

and Compliance 

Time(s): 

Required as indicated, unless accomplished previously: 

(1) For helicopters that have not yet been modified in accordance with ECD 

ASB MBB BK117 C-2-24A-008 Revision 1, within 300 flight hours (FH) 

or 6 months, whichever occurs first after 19 August 2011 [the effective 

date of the original issue of this AD], accomplish the following actions in 

accordance with the instructions of ECD ASB MBB-BK117 C-2-24A010: 

(1.1) Identify the P/N and modification status of each GCU installed on 

the helicopter, and 

(1.2) If a GCU, identified as required by paragraph (1.1) of this AD, is 

listed in Table 1 of this AD, replace that GCU with a serviceable 

unit. 

Table 1 – Affected GCU 

Part Number Mod. Status 

“no MOD” 

P/N 51530-021EI “MOD A” 

“MOD B” 

(2) From 19 August 2011 [the effective date of the original issue of this AD], 

do not install on any helicopter a GCU which is listed in Table 1 of this 

AD. 

(3) For helicopters that have already been modified in accordance with 

ECD ASB MBB BK117 C-2-24A-008 Revision 1, accomplish the actions 

as specified in paragraphs (1.1) and (1.2) of this AD within 1 500 FH or 

16 calendar months, whichever occurs first after 19 August 2011 [the 

effective date of the original issue of this AD], in accordance with the 

instructions of ECD ASB MBB-BK117 C-2-24A-010. 

Ref. Publications: ECD ASB MBB BK117 C-2-24A-008 Revision 1 dated 29 August 2011. 

ECD ASB MBB-BK117 C-2-24A-010 Revision 1 dated 01 July 2011, and 

Revision 2 dated 14 September 2011. 

The use of later approved revisions of these documents 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. The original issue of this AD was posted on 06 June 2011 as PAD 11-

058 for consultation until 04 July 2011 and republished on 12 July 2011 

as PAD 11-058R1 for extended consultation until 26 July 2011. 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: 

Eurocopter Deutschland GmbH, Industriestrasse 4, 

86607 Donauwörth, Federal Republic of Germany 

Telephone: + 49 (0)151-1422 8976; Facsimile: + 49 (0)906-71 4111.