# AD 90-23-03: Main Rotor Servo Control - Type: Airworthiness directive - Status: Current - Products: Airbus Helicopters AS355E, AS355F, AS355F1, AS355F2, AS350B, AS350B1, AS350B2, AS350C, AS350D and AS350D1 - Effective: December 3, 1990 - Published: November 2, 1990 - Issued: October 9, 1990 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Rotorcraft - Amendment: 39-6777 - Docket: 89-ASW-66 - Registered aircraft: 261 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/BC0A1518E268E19A86256A4D006AD4CB.0001 - DRS record last changed: November 21, 2025 - Page: https://openairdocs.org/ad/90-23-03 ## The airworthiness directive 90-23-03 AEROSPATIALE (SOCIETE NATIONALE INDUSTRIELLE AEROSPATIALE): Amendment 39-6777. Docket No. 89-ASW-66. Applicability: Model AS 350 and AS 355 series helicopters, with Dunlop main rotor servo controls, part numbers (P/N) AC 64182, AC 67030, AC 66442, and AC 67034 installed. Compliance: Required as indicated, unless already accomplished. To prevent failure or malfunction of the main rotor servo controls due to icing, which could result in loss of control of the helicopter, accomplish the following: (a) Within the next 300 hours' time in service, install a protective cover on each main rotor servo control in accordance with the Accomplishment Instructions of Aerospatiale Service Bulletin No. 67.11, dated March 23, 1989, or 67.14, dated April 18, 1990, as applicable. (b) An alternate method of compliance or adjustment of the compliance times, which provides an equivalent level of safety, may be used if approved by the Manager, Rotorcraft Standards Staff, ASW-110, Rotorcraft Directorate, Aircraft Certification Service, Fort Worth, Texas 76193-0110. The installation procedures shall be done in accordance with Aerospatiale Service Bulletin No. 67.11, dated March 23, 1989, or 67.14, dated April 18, 1990, as applicable. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Aerospatiale Helicopter Corporation, 2701 Forum Drive, Grand Prairie, Texas 75053-4005. Copies may be inspected at the Rules Docket in the Office of the Assistant Chief Counsel, FAA, 4400 Blue Mound Road, Bldg. 3B, Room 158, Fort Worth, Texas, or at the Office of the Federal Register, 1100 L Street, N.W., Room 8301, Washington, DC. This amendment (39-6777, AD 90-23-03) becomes effective on December 3, 1990. ## Affected data sheets (2) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS H9EU](https://openairdocs.org/tcds/H9EU): Airbus Helicopters; names 6 of 10 models: AS350C, AS350B, AS350D1, AS350B2, AS350B1, AS350D - [TCDS H11EU](https://openairdocs.org/tcds/H11EU): Airbus Helicopters; names 4 of 6 models: AS355F2, AS355F1, AS355E, AS355F ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 261 (261 by airframe model, 0 by engine model) - Makers: Eurocopter 147, Aerospatiale 47, American Eurocopter 38, Airbus Helicopters 11, Eurocopter France 10, S N I A S 7, Airbus Helicopter 1 Models with the most aircraft: - [Eurocopter AS 350 B2](https://openairdocs.org/model/eurocopter-as-350-b2): 146 aircraft (airframe model) - [American Eurocopter AS350B2](https://openairdocs.org/model/american-eurocopter-as350b2): 38 aircraft (airframe model) - [Aerospatiale AS350B](https://openairdocs.org/model/aerospatiale-as350b): 13 aircraft (airframe model) - [Aerospatiale AS350B2](https://openairdocs.org/model/aerospatiale-as350b2): 11 aircraft (airframe model) - [Airbus Helicopters AS350B2](https://openairdocs.org/model/airbus-helicopters-as350b2): 10 aircraft (airframe model) - [Aerospatiale AS 355F1](https://openairdocs.org/model/aerospatiale-as-355f1): 9 aircraft (airframe model) - [Eurocopter France AS350B2](https://openairdocs.org/model/eurocopter-france-as350b2): 8 aircraft (airframe model) - [Aerospatiale AS 355F2](https://openairdocs.org/model/aerospatiale-as-355f2): 6 aircraft (airframe model) - [S N I A S AS-350B ECUREUIL](https://openairdocs.org/model/s-n-i-a-s-as-350b-ecureuil): 5 aircraft (airframe model) - [Aerospatiale AS355F2 ECUREUIL](https://openairdocs.org/model/aerospatiale-as355f2-ecureuil): 3 aircraft (airframe model) - [Aerospatiale AS355F TWINSTAR](https://openairdocs.org/model/aerospatiale-as355f-twinstar): 2 aircraft (airframe model) - [Aerospatiale AS350B1 ECUREUIL](https://openairdocs.org/model/aerospatiale-as350b1-ecureuil): 2 aircraft (airframe model) - [S N I A S AS350D ASTAR](https://openairdocs.org/model/s-n-i-a-s-as350d-astar): 1 aircraft (airframe model) - [Aerospatiale AS-355E TWIN STAR](https://openairdocs.org/model/aerospatiale-as-355e-twin-star): 1 aircraft (airframe model) - [Airbus Helicopter AS355F1](https://openairdocs.org/model/airbus-helicopter-as355f1): 1 aircraft (airframe model) - [S N I A S AS 355F](https://openairdocs.org/model/s-n-i-a-s-as-355f): 1 aircraft (airframe model) - [Eurocopter AS350B](https://openairdocs.org/model/eurocopter-as350b): 1 aircraft (airframe model) - [Eurocopter France AS350B](https://openairdocs.org/model/eurocopter-france-as350b): 1 aircraft (airframe model) - [Airbus Helicopters AS355F2](https://openairdocs.org/model/airbus-helicopters-as355f2): 1 aircraft (airframe model) - [Eurocopter France AS355F2](https://openairdocs.org/model/eurocopter-france-as355f2): 1 aircraft (airframe model) All 21 models: https://openairdocs.org/ad/90-23-03/models.md Every aircraft: https://openairdocs.org/ad/90-23-03/aircraft.md Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.