EASA AD No.: 2008-0007R3

EASA Form 110 Page 1/4 

## EASA AIRWORTHINESS DIRECTIVE

AD No.: 2008-0007R3

Date: 12 May 2010

Note: This Airworthiness Directive (AD) is issued b y EASA, acting in accordance with Regulation (EC) No 216/2008 on behalf of the European Communit y, its Member States and of the European third countries that participate in the ac tivities 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 en sured by accomplishing any applicable ADs. Conseque ntly, no person may operate an aircraft to which an AD applies, except in accor dance with the requirements of that AD, unless othe rwise specified by the Agency [EC 2042/2003 Annex I, Part M.A.303] or agreed with the Authority of the State of Registry [EC 216/200 8, Article 14(4) exemption].



### Type Approval Holder’s Name :

EUROCOPTER Type/Model designation(s) :

EC 225 LP helicopters

TCDS Number : EASA.R.002

Foreign AD : Not applicable

Revision : This AD revises EASA AD 2008-0007R2 dat ed 17 December 2008



### ATA 04, 63 Limitations – 14Hz Vibrations at Low Den sity Altitude

Manufacturer(s): EUROCOPTER

Applicability: EC 225 LP helicopters, all serial nu mbers, if: - not equipped of all three modifications MOD 07265 82, MOD 0726477 and MOD 0726583, or, - if not equipped of MOD 0726592, or, - if equipped with all three modifications MOD 0726 606, MOD 0726610, MOD 0726611 and missing accomplishment of MOD 0726632.

Note 1:
Above referenced MODs are modifications accomplishe d during production. In order to determine in-service accomplishment Servic e Bulletins of these modifications, refer to EUROCOPTER EC 225 Alert Ser vice Bulletin No.
04A001 revision 3.

Reason: Due to the main rotor control linkage desig n, there is a coupling between the Main Gearbox (MGB) motion and the main servo-contro l inputs. In certain flight conditions with increased air density, this generates spurious 14Hz control inputs in the main rotor which, in return, transfers dynamic loads to the structure, with feedback on the MGB motion, inducin g a continuous vibration phenomenon. Flight tests have shown that there is a density altitude (H σ ) limit below which the occurrence of the vibration phenome non is significantly increased or even diverges, which could lead to the loss of control of the helicopter. Pending availability of the Rotorcraft Flight Manuals’ (RFM) revisions, EASA issued Emergency AD 2006-0056-E to require limiting the flight envelope, mitigating the risk of recurrence of the vibration phenomenon.EASA AD No.: 2008-0007R3

EASA Form 110 Page 2/4 Subsequently, EUROCOPTER developed modification (MO D) 0726532 relating to VMS software, MOD 0726477 relating to s ervo-controls with attenuated dynamic response and MOD 0726536 relatin g to FADEC software.
Embodiment of these three modifications aimed to re lieve the affected helicopters of the required flight envelope limitat ions. AD 2006-0056 Revision 1 was therefore issued to update the “Applicability ” paragraph with information that when MOD 0726532, MOD 0726477 and MOD 0726536 were all installed together, this was considered as an optional termin ating action, allowing the flight envelope limitations to be removed. In addit ion, AD 2006-0056 R1 took into account the availability of RFM revisions cont aining the required altitude
limitations in order to relieve the need of maintai ning a copy of this AD in the

RFM.

Later on, flight test campaign and analysis showed that even with the 3 referenced MODs installed, the spurious 14Hz vibrat ion phenomenon may not be totally precluded from the re-established flight envelope for certain flight conditions. Therefore, VMS and FADEC software versi ons have been upgraded, redefining the optional terminating actio n so that respectively, MOD 0726532 has been replaced with MOD 0726582 (VMS sof tware version V11.01) and MOD 0726536 has been replaced with MOD 0726583 (FADEC software version V2.4.5) and the RFM revisions ment ioned before have been amended accordingly.

For the reasons described above, AD 2008-0007 was i ssued to retain the requirements of AD 2006-0056 R1 which was supersede d, imposing limitations on the flight envelope as originally specified, and redefining the optional terminating action that allowed operators to become relieved from the limitation to operate below -2 000 feet H σ , by accomplishing MOD 0726582, MOD 0726477 and MOD 0726583 (modifications which permit to operate up to the
certification H σ of -3.500 feet), and by requiring the implementati on of updated
versions of the RFM Conditional Revisions RCe relev ant to these 3
modifications.

Revision 1 of this AD was issued to take into accou nt the certification of a flight envelope expansion that occurred in the meantime and which has resulted in a new definition of the limitations imposed by paragr aph (1) of this AD. In addition, it aimed to correct incomplete references to RFM Co nditional Revisions RCe in paragraph (3) of this AD and to add paragraph (4) t o clarify the optional terminating action for the requirements of this AD.

Revision 2 of this AD was issued to correct the tex t of the limitation (density altitude instead of pressure altitude) in paragraph (1) so that it remained
consistent with the title of the AD and with RFM re visions contents.

Thereafter, EUROCOPTER has on one hand designed MOD 0726592 (new MAKILA 2A1 engines, including MOD 0726583 and requi ring MOD 0726582 and MOD 0726477) and on the other hand continued it s development work for expansion of the flight envelope towards a lower H σ . The last led to the approval of several new modifications allowing the expansion the flight envelope up to - 6,000 feet H σ with no risk that the vibration phenomenon

occurs.

The - 6,000 feet H σ is possible when the helicopter is modified with t he MOD 0726632 (-6,000 feet H σ flight envelope) which encompasses a batch of associated modifications: previous MOD 0726477 (att enuated servo-controls) and new MOD 0726610 (FADEC software update, version V12), MOD 0726611(VMS software update, version V2.4.6), MOD 0 726606 (Autopilot software version S9.51) and also complementary MOD 0726631 (relevant wiring provisions).

Revision 3 of this AD is now issued : - to take into account the approval of these new mo difications (that are an alternative optional terminating actions for the requirements of this AD), - to inform which helicopters remain subject to the limit of operation at -2,000 feet H σ , and,EASA AD No.: 2008-0007R3

EASA Form 110 Page 3/4 - to require the RFM update with appropriate RFM re visions that results of latest modifications approval.

Effective Date: 26 May 2010.

Required Action(s) and Compliance Time(s): Required as indicated, unless accomplished previous ly:

(1) On each flight as from March 01, 2006 [the effe ctive date of Emergency AD 2006-0056-E], comply with the flight envelope li mitation specified
below:

Operation below -2 000 feet (-610 m) density altitu de (H σ ) is
PROHIBITED.

(2) Within 30 days after the effective date of this AD, ensure that the Rotorcraft Flight Manual is updated with the follow ing revisions, as applicable:

- For standard EC 225 LP helicopters (equipped with air intakes fitted with screens): Normal Revision RN11 (10-04) in comb ination with Conditional Revision RCe (10-04),

or

- For EC 225 LP helicopters equipped with MPAI (mul ti purpose air intakes): Normal Revision RN21 (10-05) in combinati on with Conditional Revision RCe (10-04).

(3) At the operator’s discretion, accomplishment on any helicopter of either all three modifications MOD 0726582, MOD 0726477, MOD 0 726583, or the MOD 0726592, or all three modifications MOD 0726606 , MOD 0726610, MOD 0726611 in conjunction of MOD 0726632, the limi tation and RFM Conditional revisions imposed by paragraphs (1) and (2) of this AD are no longer required for that helicopter.

Note 2:

MOD 0726592 (MAKILA 2A1 engines) includes MOD 07265 83 (FADEC software V11.01) and requires also MOD 0726582 (VMS software V2.4.5) and MOD 0726477 (servo-controls with attenu ated dynamic response).

Note 3:

MOD 0726610 (FADEC software update, version V12) an d MOD 0726611 (VMS software update, version V2.4.6) repla ce MOD 0726583 and MOD 0726582 respectively. The two new modificat ions MOD 0726610, MOD 0726611 must always be accomplished to gether and also jointly with MOD 0726606 (Autopilot software v ersion S9.51).

Note 4:

MOD 0726632 (H σ = -6,000 feet flight envelope) requires all three modifications MOD 0726610, MOD 0726611, MOD 0726606 have been accomplished and imposes also the MOD 0726477 and c omplementary MOD 0726631 (wiring provisions for low H σ flight envelope).

Ref. Publications: EUROCOPTER EC 225 Alert Service Bulletin No. 04A001 revision 3.

Normal Revision RN11 (10-04) / Conditional Revision RCe (10-04).EASA AD No.: 2008-0007R3

EASA Form 110 Page 4/4 Normal Revision RN21 (10-05) / Conditional Revision RCe (10-04).

The use of later approved revisions of these docume nts is acceptable for compliance with the requirements of this AD.

Remarks : 1. If requested and appropriately substantiated, EA SA can approve Alternative Methods of Compliance for this AD.

2. The original issue of this AD was posted on 13 D ecember 2007 as
PAD 07-223 for consultation until 27 December 2007. No comments were received during the consultation period.

3. Enquiries regarding this AD should be referred t o the Airworthiness Directives, Safety Management & Research Section, C ertification Directorate, EASA. E-mail ADs@easa.europa.eu

4. For any question concerning the technical conten t of the requirements in this AD, please contact: EUROCOPTER (STDI) - Aéroport de Marseille Provence - 13725 Marignane Cedex – France; Telephone: +33 (0) 4 42 85 97 97; Fax: 33 (0) 4 42 85 99 66.
E-mail: Directive.technical-support@eurocopter.com