AD 73-15-03

73-15-03 AVIONS MARCEL DASSAULT: Amendment 39-1688. Applies to Fan Jet Falcon airplanes, Serial Numbers 1 thru 111, which have aluminum alloy air conditioning pipes, P/N's MY20-721-28-1 and MY20-721-61-1, installed.

Compliance is required as indicated.

To prevent leakage of very hot air into the rear compartment, accomplish the following, unless already accomplished:

(a) Within the next 100 hours' time in service after the effective date of this AD, comply with subparagraphs (1) and (2), and thereafter comply with subparagraph (1) at intervals not to exceed 200 hours' time in service from the last inspection.

(1) Visually inspect the studs which retain the SEMCA coupling on pipe, P/N MY20-721-28-1, for scoring or bending, and inspect the holes receiving those studs for stretching or elongation, in accordance with Dassault Service Bulletin No. 430 (21-30) dated February 16, 1972, or an FAA-approved equivalent.

(2) Inspect the weld beads and adjoining areas at the junction of the pipes, P/N's MY20-721-28-1 and MY20-721-61-1, for cracks using a magnifying glass of 5 power or greater and a dye penetrant, in accordance with Dassault Service Bulletin No. 430 (21-30) dated February 16, 1972, or an FAA-approved equivalent.

(b) Within the next 100 hours' time in service after the effective date of this AD or before the accumulation of 600 hours' time in service on an aluminum alloy air conditioning pipe, P/N MY 20-721-28-1 or MY20-721-61-1, whichever occurs later

(1) Replace the pipes, P/N's MY20-721-28-1 and MY20-721-61-1, with pipes of the same part number and thereafter continue to replace aluminum alloy pipes before the accumulation of 600 hours' time in service thereon and comply with paragraph (d); or

(2) Replace the pipes, P/N's MY 20-721-28-1 and MY20-721-61-1, with stainless steel pipes, P/N's MY20-721-28-2 and MY20-721-61-2, in accordance with Dassault Service Bulletin No. 442 (21-31) dated February 16, 1972, oran FAA-approved equivalent.

(c) If scoring or bending of the studs or stretching or elongation of the holes are found during an inspection specified in paragraph (a)(1) or cracks are found during an inspection specified in paragraph (a)(2) before further flight comply with subparagraph (1) or (2) of paragraph (b).

(d) For aluminum alloy pipes installed as replacement in accordance with subparagraph (1) of paragraph (b)

(1) Before the accumulation of 200 hours' time in service thereon, inspect in accordance with subparagraph (1) of paragraph (a); and

(2) Thereafter, inspect in accordance with subparagraph (1) of paragraph (a) at intervals not to exceed 200 hours' time in service from the last inspection.

(e) Operators who have not kept records of hours' time in service on pipes, P/N's MY20-721-28-1 and MY20-721-61-1, shall substitute airplane hours' time in service in lieu thereof.

(f) The inspections required by paragraphs (a) and (d) and the replacements specified in subparagraph (1) of paragraph (b) may be discontinued when the aluminum alloy air conditioning pipes, P/N's MY20-721-28-1 and MY20-721-61-1, are replaced with stainless steel pipes, P/N's MY20-721-28-2 and MY20-721-61-2, in accordance with Dassault Service Bulletin No. 442 (21-31), dated February 16, 1972, or an FAA-approved equivalent.

This amendment becomes effective August 15, 1973.