82-26-06 DeHAVILLAND: Amendment 39-4517. Applies to Model DHC-6 (serial numbers 1 through 709, 711 through 735, 737 through 753, 755 through 761, 763 through 779, and 791) airplanes which incorporate a windscreen washer/deicing system certificated in any category.
COMPLIANCE: Required as indicated unless already accomplished.
To prevent leakage of isopropyl alcohol in the crew compartment and a possible crew compartment fire, accomplish the following:
(a) Within the next 25 hours time-in-service after the effective date of this AD, and each 200 hours time-in-service thereafter inspect the windscreen washer/deicing system for evidence of leaks in accordance with the Accomplishment Instructions of DeHavilland Service Bulletin S/B No. 6/422, Revision A dated June 18, 1982.
(1) Replace any defective components which could cause leaks and ensure that all tubing is secured in accordance with Accomplishment Instructions Step 3 and Step 6.
(b) On or before November 30, 1983:
(1) Install a permanent placard having letters of 1/8 inch minimum height on or near the washer/deicing fluid tank filler which states "DO NOT USE ISOPROPYL ALCOHOL OR ISOPROPYL ALCOHOL MIXTURES."
(2) Install a placard having letters of 1/8 inch minimum height adjacent to the windscreen washer/deicing system switch which states "WASHER ONLY" and operate the airplane in accordance with these placard limitations.
(3) On airplanes certificated for flight into icing conditions, install an electrically heated windscreen in accordance with DeHavilland Modification S.0.0. 6007, Issue 7 dated May 17, 1982.
(c) The inspections per paragraph (a) of this AD need not be accomplished when the placards required by paragraph (b) are installed.
(d) The airplane may be flown in accordance with Federal Aviation Regulation 21.197 to a location where this AD can be accomplished.
(e) An equivalent method of compliance with this AD may be used if approved by the Manager, New York Aircraft Certification Office, ANE-170, Federal Aviation Administration, 181 South Franklin Avenue, Room 202, Valley Stream, New York 11581, telephone: (516) 791-6680.
This amendment becomes effective on December 27, 1982.