AD 91-14-15 ACTIVE

91-14-15 HOFFMANN AIRCRAFT, LTD.: Amendment 39-7056. Docket No. 90-CE-51- AD.

Applicability: Model H-36 Dimona motor gliders (serial numbers 3501 through 36143) that were supplied or equipped with a fuel tank made of glass fiber reinforced plastic (GFRP) or fiber reinforced plastic (FRP), certificated in any category.

Compliance: Required as indicated after the effective date of this AD, unless already accomplished.

To avoid engine shutdown caused by solid or rubber-like gelcoat fuel deposits, accomplish the following:

(a) Within the next 50 hours time-in-service (TIS) or within the next 6 calendar months, whichever occurs first, accomplish the following:

(1) Statically ground the glider and the fuel system.

(2) Empty the fuel tank through a drainer, ventilate the tank, and then remove the tank.

(3) Remove the gasoline filter and inspect the filter and the fuel lines for solid or rubber-like deposits. Remove any solid or rubber-like deposits and thoroughly clean the filter.

(4) Replace the GFRP or FRP fuel tank with an aluminum tank, Part Number 820.5.12 S3a, and reinstall the gasoline filter and reconnect the fuel lines.

(5) Using pen and ink, correct the glider weight and balance data sheet as follows:

(i) Decrease the empty weight by 2.2 pounds (1kg).

(ii) Show a forward shift of 0.06 inches (1.5mm) of the empty weight center of gravity value.

(6) Using pen and ink, change the Maintenance and Inspection checklist, page 36 of the maintenance manual, by adding the following notations:

(i) "14. Check fuel lines and tank assembly for security and leaks."

(ii) Enter the symbol "0" in columns marked "100 hours" and "500 hours".

(b) If the aluminum tank required by paragraph (a)(4) of this AD has been ordered, but is not available, within the next 50 hours TIS or 6 calendar months after the effective date of this AD, whichever occurs first, and thereafter at intervals not toexceed 100 hours TIS or 12 calendar months, whichever occurs first, accomplish the following interim actions:

(1) Statically ground the glider and the fuel system.

(2) Empty the fuel tank through a drainer, ventilate the tank, and then remove the tank.

(3) Remove the gasoline filter and inspect the filter and the fuel lines for solid or rubber-like deposits. Remove any solid or rubber-like deposits and thoroughly clean the filter.

(4) Remove the finger filter and inspect it for solid or gelatinous deposits, remove any solid or gelatinous deposits, and thoroughly clean the filter.

(5) Perform the following inspections on the inner side of the fuel tank:

(i) Inspect for deposits through the filler hole with a mirror and light.

(ii) Inspect for softened spots in the gelcoat with a wood spatula.

(A) If no deposits or soft spots are found in the fuel tank as a result of these inspections, the glider may be operated until the fuel tank specified in paragraph (a)(4) of this AD becomes available.

(B) If any deposits or soft spots are found in the tank as a result of these inspections, prior to further flight, replace the fuel tank in accordance with the instructions of paragraph (a) of this AD.

(c) An alternative method of compliance or adjustment of the initial or repetitive compliance times that provides an equivalent level of safety may be approved by the Manager, Brussels Aircraft Certification Office, 15 Rue de la Loi, B-1040 Brussels Belgium, c/o American Embassy APO, New York, New York 09667. The request should be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Brussels Aircraft Certification Office.

(d) Information that is related to this AD may be obtained from the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri.

This amendment (39-7056, AD 91-14-15) becomes effective on August 12, 1991.