# AD 86-14-01: Attitude Heading Reference System - Type: Airworthiness directive - Status: Current - Products: ATR - GIE Avions de Transport R gional ATR42-200, ATR42-300, ATR42-320, ATR42-500, DHC-8-101, DHC-8-102, DHC-8-103, DHC-8-106, DHC-8-201, DHC-8-202, DHC-8-301, DHC-8-311 and 10 more - Effective: July 14, 1986 - Superseded by: Nothing supersedes this AD - Product type: Appliance - Amendment: 39-5340 - Registered aircraft: 408 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/EF28DF29D7C70ADE86256A3800492FE3.0001 - DRS record last changed: January 21, 2026 - Page: https://openairdocs.org/ad/86-14-01 ## The airworthiness directive 86-14-01 SPERRY CORPORATION, AEROSPACE AND MARINE GROUP: Amendment 39-5340. Applies to Sperry Corporation AHZ-600 Attitude Heading Reference System (AHRS), known to be installed in, but not limited to, DeHavilland Model DHC-8, British Aerospace Model BAe 125-800, Cessna Model 650, and Aerospatiale Model ATR-42 series airplanes, certificated in any category. Compliance is required within 30 days after the effective date of this AD, unless previously accomplished. To prevent loss of attitude/heading reference information, accomplish the following: A. Modify the Sperry Corporation AH-600 Strapdown Attitude and Heading Reference Unit (AHRU) by incorporating modifications in accordance with the following Sperry Service Bulletins or later revisions approved by the Manager, Western Aircraft Certification Office, FAA, Northwest Mountain Region: 21-1985-175, dated April 7, 1986 (Modification T); 21-1985-186, dated April 7, 1986 (Modifications S & V); 21-1985-187,dated April 7, 1986 (Modification U); 21-1986-19, dated April 22, 1986 (Modification Z); 21-1986-20, dated April 22, 1986 (Modification AA); and 21-1986-29, dated April 22, 1986 (Modification AB). B. Alternate means of compliance which provide an acceptable level of safety may be used when approved by the Manager, Western Aircraft Certification Office, FAA, Northwest Mountain Region. C. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Sperry Corporation, Aerospace & Marine Group, P.O. Box 29000, Phoenix, Arizona 85038-9000. These documents may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or the Western Aircraft Certification Office,15000 Aviation Boulevard, Hawthorne, California. This amendment becomes effective July 14, 1986. ## Affected data sheets (4) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A13NM](https://openairdocs.org/tcds/A13NM): De Havilland Aircraft of Canada Limited; names 12 of 16 models: DHC-8-101, DHC-8-102, DHC-8-103, DHC-8-106, DHC-8-201, DHC-8-202, DHC-8-301, DHC-8-311… - [TCDS A53EU](https://openairdocs.org/tcds/A53EU): ATR – GIE Avions de Transport Régional; names 4 of 11 models: ATR42-300, ATR42-320, ATR42-200, ATR42-500 - [TCDS A3EU](https://openairdocs.org/tcds/A3EU): Textron Aviation Inc.; names 2 of 50 models: BAe.125 Series 800A (U-125), BAe.125 Series 800B - [TCDS A9NM](https://openairdocs.org/tcds/A9NM): Textron Aviation Inc.; names 1 of 1 models: 650 ## 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: 408 (408 by airframe model, 0 by engine model) - Makers: Cessna 201, British Aerospace 66, Bombardier 57, Dehavilland 28, Aerospatiale/Aeritalia 16, Corporate Jets 8, Raytheon Corporate Jets 8, Atr-Gie Avions De Trnsp Region 6, Boeing Of Canada/Dehav Div 6, Aerospatiale/Alenia 3 Models with the most aircraft: - [Cessna 650](https://openairdocs.org/model/cessna-650): 201 aircraft (airframe model) - [British Aerospace BAE 125 SERIES 800A](https://openairdocs.org/model/british-aerospace-bae-125-series-800a): 61 aircraft (airframe model) - [Bombardier DHC-8-402](https://openairdocs.org/model/bombardier-dhc-8-402): 26 aircraft (airframe model) - [Dehavilland DHC-8-202](https://openairdocs.org/model/dehavilland-dhc-8-202): 17 aircraft (airframe model) - [Bombardier DHC-8-315](https://openairdocs.org/model/bombardier-dhc-8-315): 15 aircraft (airframe model) - [Bombardier DHC-8-202](https://openairdocs.org/model/bombardier-dhc-8-202): 14 aircraft (airframe model) - [Aerospatiale/Aeritalia ATR 42-300](https://openairdocs.org/model/aerospatiale-aeritalia-atr-42-300): 12 aircraft (airframe model) - [Corporate Jets BAE 125-800A](https://openairdocs.org/model/corporate-jets-bae-125-800a): 8 aircraft (airframe model) - [Raytheon Corporate Jets BAE 125-800A](https://openairdocs.org/model/raytheon-corporate-jets-bae-125-800a): 8 aircraft (airframe model) - [Atr-Gie Avions De Trnsp Region ATR42-500](https://openairdocs.org/model/atr-gie-avions-de-trnsp-region-atr42-500): 6 aircraft (airframe model) - [British Aerospace BAE 125-800A](https://openairdocs.org/model/british-aerospace-bae-125-800a): 5 aircraft (airframe model) - [Dehavilland DHC-8-106](https://openairdocs.org/model/dehavilland-dhc-8-106): 4 aircraft (airframe model) - [Aerospatiale/Aeritalia ATR 42-320](https://openairdocs.org/model/aerospatiale-aeritalia-atr-42-320): 4 aircraft (airframe model) - [Boeing DHC-8-102](https://openairdocs.org/model/boeing-dhc-8-102): 3 aircraft (airframe model) - [Boeing Of Canada/Dehav Div DHC-8-311](https://openairdocs.org/model/boeing-of-canada-dehav-div-dhc-8-311): 3 aircraft (airframe model) - [Boeing Of Canada/Dehav Div DHC-8-106](https://openairdocs.org/model/boeing-of-canada-dehav-div-dhc-8-106): 2 aircraft (airframe model) - [Bombardier DHC-8-201](https://openairdocs.org/model/bombardier-dhc-8-201): 2 aircraft (airframe model) - [Dehavilland DHC-8-201](https://openairdocs.org/model/dehavilland-dhc-8-201): 2 aircraft (airframe model) - [Dehavilland DHC-8-103](https://openairdocs.org/model/dehavilland-dhc-8-103): 2 aircraft (airframe model) - [Dehavilland DHC-8-315](https://openairdocs.org/model/dehavilland-dhc-8-315): 2 aircraft (airframe model) All 30 models: https://openairdocs.org/ad/86-14-01/models.md Every aircraft: https://openairdocs.org/ad/86-14-01/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.