71-14-05: Possible Explosion in Bays 9 and 2

71-14-05 de HAVILLAND AIRCRAFT of CANADA, LTD: Amdt. 39-1242. Applies to de Havilland Model DHC-6 Series airplanes modified in accordance with JB Systems, Inc. STC SA1837WE. Compliance required within the next 10 hours' time in service after the effective date of this AD. To prevent possible explosion in bays 9 and 10 due to the operation of electrical components, accomplish the following, unless already accomplished: Deactivate the JB Systems air conditioner by disconnecting the source of power at the distribution bus, until the F.S. 281 bulkhead and other areas are sealed, per JB Systems, Inc., Service Bulletin No. 011, dated June 8, 1971, or later FAA approved revisions, or an equivalent sealing process is performed upon approval by the Chief, Aircraft Engineering Division, FAA Western Region. This amendment is effective upon publication in the Federal Register, except for all operators in receipt of this AD, by letter dated June 24, 1971, from FAA Aeronautical Center, Oklahoma City, Oklahoma. As to these operators, this AD is effective upon receipt of said letter. This amendment is effective upon publication in the Federal Register except for those recipients of letters dated June 24, 1971, which contained this amendment.