# AD 85-01-01: Acrylic Windows - Type: Airworthiness directive - Status: Current - Products: Textron 100, 65-88, 65-90, 65-A90, A100, B90 and C90 - Effective: February 6, 1985 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Small airplane - Amendment: 39-4974 - Registered aircraft: 318 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/12497B0CBCFAAC7A862569B300528590.0001 - DRS record last changed: January 21, 2026 - Page: https://openairdocs.org/ad/85-01-01 ## The airworthiness directive 85-01-01 BEECH: Amendment 39-4974. Applies to Models 65-88 (S/Ns LP-1 through LP-26, LP-28, and LP-30 through LP-47); 65-90, 65-A90, B90, and C90 (S/Ns LJ-1 through LJ-680); E90 (S/Ns LW-1 through LW-178); 100 and A100 (S/Ns B-1 through B-226); and B100 (S/Ns BE-1 through BE-8) certificated in any category in which all cast acrylic windows have not been replaced with stretched acrylic windows. Compliance: Required as indicated, unless already accomplished. To prevent failures of a cast acrylic window and resulting decompression and possible occupant injury, accomplish the following: (a) Within 50 hours time-in-service (TIS) after the effective date of this AD or 300 hours TIS after the last inspection per AD 81-12-01 whichever occurs later, and each 300 hours TIS thereafter, and within 50 hours TIS after any stripping and repainting in the area of the window; (1) Visually inspect each cast acrylic window in accordance with Beech Service Bulletin No. 2011 (SB2011). (2) If the above inspection discloses any crack, fissure, stress craze or scratch in any window, prior to further pressurized flight, replace this window with a stretched acrylic window of the appropriate part number specified in Paragraph (b). (b) Within one calendar year after the effective date of the AD, replace each cast acrylic window with one of the stretched acrylic windows listed below. WINDOW BEECH PART NUMBER Oval, baggage area 50-440014-837 or -838 Cockpit, side, standard 50-420066-317 or -318 Cockpit, side, oversize 50-420066-353 or -354 Round, Cabin 50-420013-1053 NOTE: After installing a stretched acrylic window make an appropriate entry in the Aircraft Maintenance Record which, along with previous entries, clearly shows each location at which a stretched acrylic window has been installed. (c) Upon installation of all stretched acrylic windows per Paragraph (b), this AD is no longer applicable. (d) Compliance with Paragraphs (a) and (b) is not required if the pressurization system is deactivated as follows, and the aircraft is operated in accordance with this limitation: (1) Secure the "Test/Dump" switch in the "Dump" position; and (2) Fabricate a placard, "CABIN PRESSURIZATION PROHIBITED" of 3/16-inch or larger letters and install it on the control panel adjacent to pressurization system controls; and (3) Insert a copy of this AD in the "Limitations" section of the airplane flight manual. (4) Make an appropriate entry in the Aircraft Maintenance Record showing compliance with this paragraph. (5) The provisions of this paragraph may be accomplished by the holder of at least a private pilot certificate issued under Part 61 of the Federal Aviation Regulations on any airplane owned or operated by that person, provided the airplane is not used in air carrier service. (e) Aircraft may be flown unpressurized in accordance with FAR 21.197 to a location where the inspections/repairs required by this AD can be performed. (f) An equivalent method of compliance with this AD may be used when approved by the Manager, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid- Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4400. This AD supersedes AD 81-12-01, Amendment 39-4126. This amendment becomes effective February 6, 1985. ## Affected data sheets (2) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS 3A20](https://openairdocs.org/tcds/3A20): Textron Aviation Inc.; names 5 of 22 models: B90, 65-88, 65-A90, 65-90, C90 - [TCDS A14CE](https://openairdocs.org/tcds/A14CE): Textron Aviation Inc.; names 2 of 12 models: A100, 100 ## 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: 318 (318 by airframe model, 0 by engine model) - Makers: Beech 318 Models with the most aircraft: - [Beech C90](https://openairdocs.org/model/beech-c90): 216 aircraft (airframe model) - [Beech 65-A90](https://openairdocs.org/model/beech-65-a90): 34 aircraft (airframe model) - [Beech B90](https://openairdocs.org/model/beech-b90): 29 aircraft (airframe model) - [Beech A100](https://openairdocs.org/model/beech-a100): 15 aircraft (airframe model) - [Beech 100](https://openairdocs.org/model/beech-100): 14 aircraft (airframe model) - [Beech 65-90](https://openairdocs.org/model/beech-65-90): 7 aircraft (airframe model) - [Beech 65-88](https://openairdocs.org/model/beech-65-88): 3 aircraft (airframe model) All 7 models: https://openairdocs.org/ad/85-01-01/models.md Every aircraft: https://openairdocs.org/ad/85-01-01/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.