# AD 89-18-13: AFM Changes - APU - Type: Airworthiness directive - Status: Current - Products: Textron BAe.125 Series 1000A, BAe.125 Series 1000B, BAe.125 Series 800A, BAe.125 Series 800A (C-29A), BAe.125 Series 800A (U-125), BAe.125 Series 800B, BH.125 Series 400A, BH.125 Series 600A, DH.125 Series 1A, DH.125 Series 1A-522, DH.125 Series 1A/R-522, DH.125 Series 1A/S-522 and 30 more - Effective: September 28, 1989 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-6309 - Docket: 89-NM-24-AD - Registered aircraft: 133 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/209DA7E0CF9D9BF6862569F300525764.0001 - DRS record last changed: January 21, 2026 - Page: https://openairdocs.org/ad/89-18-13 ## The airworthiness directive 89-18-13 BRITISH AEROSPACE: Amendment 39-6309. (Docket No. 89-NM-24-AD) Applicability: Model DH/HS/BH/BAe 125 series airplanes certificated in any category, equipped with Sundstrand Turbomach Titan Gas Turbine Auxiliary Power (APU) Unit, Model T- 62T Series, installed in the aft equipment compartment of the airplane. NOTE: Installation of the subject APU's has been in accordance with, but are not limited to, the following Supplemental Type Certificates (STC): SA674CE SA1143EA SA1176EA SA1196EA SA440NE SA1173EA SA4710SW SA1923SW This AD applies to all Sundstrand Turbomach Titan APU installations in the aft equipment compartment. Compliance: Required as indicated unless previously accomplished. To prevent a fire in the aft equipment compartment, puncture of the aft pressure bulkhead, and severance of the control cables, due to an uncontained APU rotor failure, accomplish the following: A. Within the next 10 days after the effective date of this AD: 1. Revise the Limitations Section in the FAA-approved Airplane Flight Manual (AFM) Supplement to include the following statement. This may be accomplished by inserting a copy of this AD in the AFM Supplement Limitations Section: "OPERATION OF THE APU DURING FLIGHT IS PROHIBITED, EXCEPT DURING AN EMERGENCY." 2. Install a placard next to the APU start switch in the cockpit to state: "OPERATION OF THE APU DURING FLIGHT IS PROHIBITED, EXCEPT DURING AN EMERGENCY." B. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Standardization Branch, ANM-113, FAA, Northwest Mountain Region, Transport Airplane Directorate. NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector (PMI), who will either concur or comment and then send it to the Manager, Standardization Branch, ANM-113. C. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of modifications required by this AD. This amendment (39-6309, AD 89-18-13) becomes effective on September 28, 1989. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A3EU](https://openairdocs.org/tcds/A3EU): Textron Aviation Inc.; names 40 of 50 models: BAe.125 Series 1000A, HS.125 Series 3B/RB, HS.125 Series 401B, HS.125 Series 600A, HS.125 Series 600B/2, HS.125 Series 403A(C), HS.125 Series 600B/1, HS.125 Series 700A… ## 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: 133 (133 by airframe model, 0 by engine model) - Makers: British Aerospace 89, Corporate Jets 17, Raytheon Corporate Jets 12, Hawker Siddeley 11, Raytheon 3, Hawker Beechcraft 1 Models with the most aircraft: - [British Aerospace BAE 125 SERIES 800A](https://openairdocs.org/model/british-aerospace-bae-125-series-800a): 61 aircraft (airframe model) - [British Aerospace HS 125-700A](https://openairdocs.org/model/british-aerospace-hs-125-700a): 14 aircraft (airframe model) - [British Aerospace BAE 125 SERIES 1000A](https://openairdocs.org/model/british-aerospace-bae-125-series-1000a): 9 aircraft (airframe model) - [Corporate Jets BAE 125-1000A](https://openairdocs.org/model/corporate-jets-bae-125-1000a): 9 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) - [Hawker Siddeley HS.125 SERIES 700A](https://openairdocs.org/model/hawker-siddeley-hs-125-series-700a): 7 aircraft (airframe model) - [British Aerospace BAE 125-800A](https://openairdocs.org/model/british-aerospace-bae-125-800a): 5 aircraft (airframe model) - [Raytheon Corporate Jets BAE 125-1000A](https://openairdocs.org/model/raytheon-corporate-jets-bae-125-1000a): 4 aircraft (airframe model) - [Hawker Siddeley BH.125-400A](https://openairdocs.org/model/hawker-siddeley-bh-125-400a): 2 aircraft (airframe model) - [Hawker Siddeley DH.125-3A/RA](https://openairdocs.org/model/hawker-siddeley-dh-125-3a-ra): 2 aircraft (airframe model) - [Raytheon BAE 125-800A](https://openairdocs.org/model/raytheon-bae-125-800a): 2 aircraft (airframe model) - [Hawker Beechcraft BAE 125-800B](https://openairdocs.org/model/hawker-beechcraft-bae-125-800b): 1 aircraft (airframe model) - [Raytheon HS 125-700A](https://openairdocs.org/model/raytheon-hs-125-700a): 1 aircraft (airframe model) All 16 models: https://openairdocs.org/ad/89-18-13/models.md Every aircraft: https://openairdocs.org/ad/89-18-13/aircraft.md ## Related documents - [STC SA1143EA](https://openairdocs.org/stc/SA1143EA): Limited to installation on model DH.125-1A, serial number 25091 ONLY.. PATS Aircraft LLC, Cited in the text - [STC SA1173EA](https://openairdocs.org/stc/SA1173EA): Rework of Solar T-62T-39 APU installed by STC SA674CE when Garrett AiResearch TFE-731-3-1H engines are installed per STC SA3870WE.. PATS Aircraft LLC, Cited in the text - [STC SA1176EA](https://openairdocs.org/stc/SA1176EA): Installation of Solar T-62T-40C APU when Garrett AiResearch TFE-731-3-1H engines are installed in accordance with STC SA3925WE.. PATS Aircraft LLC, Cited in the text - [STC SA1196EA](https://openairdocs.org/stc/SA1196EA): Installation of solar T-62T-40C APU with 400 ampere starter-generator.. PATS Aircraft LLC, Cited in the text - [STC SA1923SW](https://openairdocs.org/stc/SA1923SW): Installation of solar T62T-39 turbine auxiliary power unit with General Electric starter/generator Model No. 2CM308C1.. Textron Aviation Inc, Cited in the text - [STC SA440NE](https://openairdocs.org/stc/SA440NE): Installation or Turbomach (Solar) T-62T-40C APU. Limited to installation on model BH.125-400A, serial number 755 ONLY.. PATS Aircraft LLC, Cited in the text - [STC SA4710SW](https://openairdocs.org/stc/SA4710SW): Installation of solar auxiliary power unit (APU) Model T62T-40C or T62T-40C8D1.. Textron Aviation Inc, Cited in the text - [STC SA674CE](https://openairdocs.org/stc/SA674CE): Installation of Solar T-62T-39Y, -39 or -40C APU modifications.. PATS Aircraft LLC, Cited in the text --- 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.