AD 61-23-01

61-23-01 BRANTLY: Amdt. 364 Part 507 Federal Register November 3, 1961. Applies to All Model B-2 Helicopters Equipped With B2-248-53 or B2-248-53A Outboard Main Rotor Blades.

Compliance required as indicated.

As the result of bond separation between the skin and foam filler on the inboard end of the B2-248-53 and -53A main rotor blades and cracks around the root fitting in both the upper and lower skins the following inspections are required:

(a) Within the next 10 hours' time in service unless already accomplished within the last 15 hours' time in service and at the expiration of each 25 hours' time in service thereafter, inspect the upper and lower skins of the inboard end of the B2-248-53 and -53A blades as follows:

(1) Inspect for bond separation by feel or sound tests. If the skin is separated from the foam filler a sponginess will be felt or a dullness in tone will be heard when tapped with a coin. Blades with voids exceeding 12 inches in length shallbe replaced prior to further flight.

(2) Inspect for cracks between rivets in the skins with a 5-power or greater magnifying glass. If any cracks are found around two or more rivets the blade must be replaced prior to further flight.

(b) When blades are replaced they must be replaced with either B2-248-53M or B2- 248-101 blades. Brantly Service Letter No. 31A must be complied with when B2-248-101 blades are installed.

(c) In addition to the inspection interval specified in (a), the inspection required in (a)(1) also must be made prior to each flight after the initial inspection.

(d) (1) The inspections required in (a) shall be made by a person as authorized by CAR 18.11. (2) The inspections required in (c) and appropriate log book entries thereon are hereby authorized to be made by the pilot.

(Brantly Service Letter No. 28A applies to this same subject.) This directive effective November 4, 1961.