AD 84-09-06

84-09-06 DeHAVILLAND: Amendment 39-4858. Applies to all Models DHC-2 MK. I (L-20A, YL-20, U-6 and U-6A), MK. II Beaver and MK. III Turbo Beaver series airplanes certificated in any category.

Compliance: Required as indicated, unless already accomplished.

To prevent the failure of the horizontal torque tube at the base of the control column which may cause loss of airplane control, accomplish the following:

(a) Within the next 5O hours time-in-service after the effective date of this AD, unless accomplished within the last 150 hours time-in-service, and subsequently at intervals thereafter not to exceed 200 hours time-in-service from the last inspection, visually inspect the control column lower sub-assembly, P/N C2CF843A (single control column) and C2CF1977AND (dual control column) for cracks in accordance with DeHavilland Service Bulletin No. 2/28, Revision B, dated May 13, 1983, Section ACCOMPLISHMENT INSTRUCTIONS paragraphs 1a, lb, 1c and If or an FAA approvedequivalent.

(b) If no cracks are found, return the airplane to service and repeat the inspections required by paragraph (a) of this AD.

(c) If cracks 0.5 inches or less in length in the weld area are found in the control column assembly P/N C2CF843A (single control column) and C2CF1977AND (dual control column), repair the above-noted assembly prior to further flight as instructed in the ACCOMPLISHMENT INSTRUCTIONS Section of Service Bulletin No. 2/28 Revision B.

(d) If cracks longer than 0.5 inches are found in the control column assembly P/N C2CF843A (single control column) and C2CF1977AND (dual control column), replace the assembly prior to further flight as instructed in the ACCOMPLISHMENT INSTRUCTIONS Section of Service Bulletin No. 2/28 Revision B.

(e) Aircraft maintenance record entries shall be made and a report in writing of the initial inspection findings, positive or negative, shall be made to the FAA, New York Aircraft Certification Office, New England Region, Attention: ANE-172, 181 South Franklin Avenue, Valley Stream, New York 11581. A negative finding report shall include the time-in-service of the aircraft and of the component. A positive finding report shall include the above information and state the location and length of any crack found. Reports may be submitted by letter to the New England Region, or through the Malfunction or Defect (M or D) procedure. (The paper work reporting requirement has been cleared by the Office of Management and Budget under Clearance Number 2100 0056.)

(f) The airplane may be flown in accordance with Federal Aviation Regulation 21.197 to a location where this AD can be accomplished.

(g) Alternate methods of compliance with this AD may be used when they provide an equivalent level of safety and are approved by the Manager, New York Aircraft Certification Office, FAA New England Region, 181 South Franklin Avenue, Valley Stream, New York 11581.

(h) The repetitive inspection intervalrequired by (a) may be increased by the Manager, New York Aircraft Certification Office, FAA New England Region upon receipt of substantiating data submitted through an FAA Maintenance Inspector.

This amendment becomes effective on May 10, 1984.