AD 74-20-09 ACTIVE

74-20-09 SIKORSKY AIRCRAFT: Amendment 39-1972 as amended by Amendment 39-2034 is further amended by Amendment 39-2829. Applies to all Sikorsky S-61A, S-61L, S- 61N, S-61R and S-61NM helicopters certificated in all categories that are equipped with S6115- 20501 series, S6115-20601 series, S6117-20101 series and S6188-15001 series main rotor blades.

Compliance required as indicated.

To prevent operation with loose or missing screws, or with cracks in the outboard end of the main rotor blades, including the tip cap and tip cap bracket, accomplish the following:

(a) Inspect main rotor blades that do not have tip cap bracket doubler P/N 61070- 15120 installed, and have less than 2,000 hours time in service on the effective date of this AD, for loose or missing screws or for cracks at the outboard end of the main rotor blade spar, tip cap, or tip cap bracket, in accordance with Section 2., paragraphs A and B., of Sikorsky Service Bulletin No. 61B15-9F, dated November 2, 1976 orlater FAA approved revisions within the next 30 hours time in service after the effective date of this AD, unless already accomplished, and at intervals thereafter within 30 hours time in service from the last inspection. If screws are missing or loose, and cannot be secured, or if there is motion in the joint between the tip cap and the blade, or if cracks are found, replace the main rotor blade or repair it in accordance with Section 2., paragraph C., of the above service bulletin prior to further flight. If a crack is found in the tip cap, tip cap attachment land, or tip cap bracket, replace or repair the main rotor blade in accordance with Section 2., paragraph B., of the above service bulletin prior to further flight.

(b) Inspect main rotor blades that do not have tip cap bracket doubler P/N 61070- 15120 installed, and have 2000 hours or more time in service on the effective date of this AD, for loose or missing screws or for cracks at the outboard end of the main rotor blade spar, tip cap, or tip cap bracket, in accordance with Section 2., paragraphs A and B, of the above Service Bulletin prior to the first flight of each day. If screws are missing or loose, and cannot be secured, or if there is motion in the joint between the tip cap and the blade, or if cracks are found, replace the main rotor blade or repair it in accordance with paragraph 2C of the above bulletin prior to further flight. If a crack is found in the tip cap, tip cap attachment land, or tip cap bracket replace or repair the main rotor blade, in accordance with Section 2., paragraph B., of the above service bulletin, prior to further flight.

(c) Inspect main rotor blades that have tip cap bracket P/N 61070-15120 installed for cracks at the outboard end of the main rotor blade spar, tip cap, and tip cap bracket, in accordance with Section 2, paragraph B., of the above bulletin, within the next 50 hours time in service after the effective date of this AD, unless already accomplished,and at intervals thereafter within 50 hours time in service from the last inspection. If a crack is found in the tip cap, tip cap attachment land, or tip cap bracket, replace or repair the main rotor blade prior to further flight, in accordance with Section 2., paragraph B., of the above bulletin.

(d) For helicopters operating at 19,500 pounds gross weight and below, inspect the outboard end of the main blades, series S6115-20501, series S6115-20601, series S6117-20101, and series S6188-15001, using the dye penetrant method, in accordance with Section 2., paragraph D., of the above Service Bulletin, within the next 200 hours time in service after the effective date of this AD, unless already accomplished, and at intervals thereafter within 200 hours time in service from the last inspection. If a crack is found, replace the main rotor blade prior to further flight.

(e) For helicopters operating above a gross weight of 19,500 pounds, inspect the outboard end of the main rotorblades using the dye penetrant method, in accordance with Section 2., paragraph D., of the above Service Bulletin, within the next 50 hours time in service after the effective date of this AD, unless already accomplished, and at intervals thereafter within 50 hours time in service from the last inspection. If a crack is found, replace the main rotor blade prior to further flight.

(f) Upon request of the operator, equivalent methods of compliance with the inspection and repair requirements of this AD may be approved by the Chief, Engineering and Manufacturing Branch, New England Region. Repetitive inspection intervals specified in this AD may be adjusted, by the Chief, Engineering and Manufacturing Branch, New England Region, to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for that operator.

Amendment 39-1972 supersedes Amendment 39-1583 (38 F.R. 1501), AD 73-02-02.

Amendment 39-1972 became effective October 4, 1974.

Amendment 39-2034 became effective December 12, 1974.

This Amendment 39-2829 becomes effective February 25, 1977.