86-23-02: Modification NB/M/990

86-23-02 PILATUS BRITTEN-NORMAN LIMITED: Amendment 39-5452. Applies to Pilatus Britten-Norman Limited (PBN) Models BN-2 and BN-2A Islander airplanes certificated in any category. Compliance: Required within the next 100 hours time-in-service after the effective date of this AD, unless already accomplished by incorporation of Modification NB/M/99O as noted in Britten-Norman Service Bulletin (S/B) No. BN.2/SB.113, Issue 2, dated April 14, 1986. To prevent undesirable oscillations, flutter or control system wear, accomplish the following: (a) Shake the elevator and aurally (by ear) determine if the mass balance weight is loose. Examine for any sign of movement, i.e., rust marks or grey lead deposits. In cases of uncertainty drill a small hole (5/32 in. dia) in the lower case and insert a probe to feel for lead movement. Alternatively dismantle the trimming weight assembly by removal of the blind riveted end covers and by removing the balance discs (note position and sequence for re- assembly). (1) If a loose balance weight is found prior to further flight, accomplish the following: (i) Remove the elevator; (ii) Drill out rivets, remove the trim weight assembly and detach the complete case from the tip rib. (iii) Lift out the profiled lead block. (iv) Clean the case internally to remove any corrosion by the use of emery cloth. Keep clean; do not wipe with oily or greasy rag or bond of adhesive will be impaired. (v) Clean the lead block to obtain a corrosion free face to the steel case and permit free fit into the case with an approximate 0.020 in. to 0.030 in. clearance. (vi) Prepare and apply a quantity of 3M's EC2216 epoxy adhesive to the case and press in the weight to obtain a layer of adhesive all around to fill the gap between the case and lead. Allow to cure approximately 12 hours at 60 degrees to 65 degrees Fahrenheit and re-assemble to the elevator structure. (vii) Re-assemble trim weights and check elevator balance, adjust trim weights if necessary to restore CAA-UK approved manufacturer's correct balance. NOTE: EC2216 may be substituted by similar "low flow" epoxy adhesive provided that the gap can be adequately sealed. (2) If no defect is found, reassemble and return the airplane to service. (b) Aircraft may be flown in accordance with Federal Aviation Regulation 21.197 to a location where this AD can be accomplished. (c) 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 documents, 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 December 8, 1986.