AD 76-13-11 R1

76-13-11 R1 SCHWEIZER: Amendment 39-2659 as amended by Amendment 39-5924. Applies to SGS 2-33, SGS 2-33A, S/N's 1 thru 424, and SGU 2-22C, CK, E, EK, S/N's 98 thru 258.

To prevent failure of the forward and aft fuselage tubular longerons due to internal corrosion caused by trapped water accomplish the following:

Within the next 30 days or 25 hours in service, whichever occurs first, after the effective date of this Airworthiness Directive, unless already accomplished, perform the following or an approved equivalent inspection.

(a) In the forward keel tube drill a No. 41 hole just ahead of the tow release slot.

(b) In the aft longerons drill a No. 41 hole approximately one inch forward of the weld cluster at the tail skid in the lower longerons.

(c) If there is any water drainage inspect for corrosion using x-ray or an approved equivalent inspection.

(d) Repair corroded parts prior to further flight, in accordance with an approved repair or replace with an unused part of the same part number or an approved equivalent part.

(e) Subsequent to the inspections, the No. 41 holes must be sealed with either a drive screw or a self plugging blind rivet. Holes may be enlarged to .125 inches for installation of a blind rivet. A waterproof sealant must be applied when installing the screw or rivet.

(f) Upon request, an equivalent means of compliance with the requirements of this AD may be approved by the Manager, New York Aircraft Certification Office, New England Region, Federal Aviation Administration, 181 South Franklin Avenue, Room 202, Valley Stream, New York 11581.

(g) Upon submission of substantiating data, by an owner or operator through an FAA Airworthiness Inspector, the Manager, New York Aircraft Certification Office, may adjust the compliance time specified in this AD.

(Schweizer Service Bulletin No. 102-33-1.1, covers this subject and is considered an approved equivalent inspection).

Amendment 39-2659, became effective July 7, 1976.

This Amendment 39-5924 amends AD 76-13-11, Amendment 39-2659 (41 FR 27029; July 1, 1976).

This Amendment 39-5924 becomes effective on May 25, 1988.