87-04-11 PILATUS BRITTEN-NORMAN LIMITED: Amendment 39-5532. Applies to Model BN-2T Islander (all serial numbers) airplanes certificated in any category.
Compliance: Required as indicated after the effective date of this AD, unless already accomplished.
To prevent the possibility of high engine vibrations and possible propeller whirl flutter, accomplish the following:
(a) Within 100 hours time-in-service (TIS) after the effective date of this AD and at each 500 hours TIS thereafter:
(1) Inspect the isolator mounting brackets, Barry Part No. 44-9115-0100, for cracks in accordance with the "Inspection (Part A) - Forged Brackets" paragraph of Pilatus Britten-Norman (PBN) Limited Service Bulletin (S/B) No. BN-2/SB.172, Issue 2, dated June 2, 1986, and:
(i) If a cracked "thick-ribbed" (0.190 inches) bracket is found, prior to further flight, replace the bracket with a similar serviceable part or
(ii) If a cracked "thin-ribbed" (0.150 inches) bracket is found, prior to further flight, replace all three brackets as an engine mounting set with "thick-ribbed"' brackets in accordance with the "Rectification (Part B) - Forged Brackets" paragraph of PBN S/B No. BN-2/SB.172, Issue 2, dated June 2, 1986.
(b) Within 100 hours TIS after the effective date of this AD, and at each 100 hours TIS thereafter:
(1) Inspect the Barry-manufactured elastomer cores, and:
(i) If Part Number (P/N) R20700-2 is installed, prior to further flight, replace such cores with stiffer serviceable cores P/N R20700-15; or,
(ii) If P/N R20700-15 is installed, inspect for cracks, tears, or delamination in accordance with the "Inspection and Rectification of Elastomer Cores (Part C)" paragraph of PBN S/B No. BN- 2/SB.172, Issue 2 dated June 2, 1986, and if defective, prior to further flight, replace with a serviceable core.
(c) The intervals between the repetitive inspections required by this AD may be adjusted up to 10 percent of the specified interval to allow accomplishing these inspections concurrent with other scheduled maintenance of the airplane.
(d) Aircraft may be flown in accordance with FAR 21.197 to a location where this AD can be accomplished.
(e) An equivalent means of compliance with this AD may be used if approved by the Manager, Aircraft Certification Staff, AEU-100, Europe, Africa, and Middle East Office, FAA, c/o American Embassy, 1000 Brussels, Belgium.
All persons affected by this directive may obtain copies of the document referred to herein upon request to Pilatus Britten-Norman Limited, Bembridge, Isle of Wight, England; or FAA, Office of the Regional Counsel, Room 1558, 601 East 12th Street, Kansas City, Missouri 64106.
This amendment becomes effective on March 9, 1987.