AD 75-08-16

75-08-16 BEECH: Amendment 39-2168. Applies to Models 65-90, 65-A90 and B90 (Serial Numbers LJ-1 through LJ-484) airplanes.

Compliance: Required as indicated, unless already accomplished.

To preclude fuel contamination in the aft fuselage area, accomplish the following:

A) On airplanes (Serial Numbers LJ-1 through LJ-395) not modified per Beechcraft Service Instruction 0230-412, Rev. I, or later approved revision, including optional Cabin Heat Out light, within 50 hours' time in service after the effective date of this AD, install a temporary placard on the heater control panel stating:

"IF HEATER FAILS TO HEAT, TURN OFF IMMEDIATELY"

and operate the aircraft in accordance with this limitation.

NOTE: This placard may be fabricated from embossed tape or typed or printed on paper of a contrasting background.

B) On airplanes (Serial Numbers LJ-1 through LJ-484) not modified in accordance with Beechcraft Service Instruction 0268-103, Rev. I, or laterapproved revision, within 50 hours' time in service after the effective date of this AD, modify the drainage and sealing of the aft fuselage area as follows:

1. Remove the tail cone and the aft fuselage access door.

2. Drill out the 5 holes in the fuselage skin just aft of the aft pressure bulkhead (station 298.0), the 2 holes just aft of the station 364.0 bulkhead, the hole just aft of the 380.0 bulkhead and the hole in the lower surface of the tail cone to .191 to .196 inch.

NOTE: In some cases some of these holes may not exist. If this is the case, do not drill new holes.

3. Fill these holes with MS20470B6 rivets of appropriate length. Seal the rivet butts with EC1239 or equivalent sealant.

4. Drill a 250 inch hole at the lower fuselage centerline .20 inch aft of the aft pressure bulkhead (fuselage station 298.20).

5. Drill a .250 inch hole in the fuselage skin at the lower fuselage centerline .44 inch aft of the fuselage station 380.0 bulkhead (just forward of the tail cone).

NOTE: Steps 4 and 5 will allow moisture to drain through the ventral fin.

6. Drill 4 .12 inch diameter drain holes in the lower edge of the ventral fin. These holes should be spaced as follows:

a. 1 hole 24.0 inches aft of the forward end of the ventral fin,

b. 1 hole 1.6 inches forward of the station 380.0 bulkhead,

c. 1 hole 22.0 inches forward of the station 380.0 bulkhead

d. 1 hole 52.0 inches forward of the station 380.0 bulkhead

7. On airplanes having a hinged aft fuselage access door, open this door, drill out the 2 drain holes in the door and 3 holes in the forward edge of the door frame.

NOTE: In some cases some of these holes may not exist. If this is the case, do not drill new holes.

a. Place tape over the 3 holes in the forward edge of the door frame. Fill these holes with EC1239 or equivalent sealant. Do not remove the tape until the sealant cures.

b. Fill the remainder of the holes with MS20470B6 rivets of appropriate length. Seal the rivet butts with EC1239 or equivalent sealant.

c. Using PPP-T-60 two (2) inch wide tape, or equivalent, temporarily seal the closed aft fuselage access door in a manner that will cover both the door opening edges and fastening screws.

C) On or before May 1, 1976, on airplanes (Serial Numbers LJ-1 through LJ-484), modify the aft fuselage in accordance with Beechcraft Service Instructions No. 0268-103, Rev. I, or later approved revisions, and on airplanes (Serial Numbers LJ-1 through LJ-395) modify the heater installation, including installation of cabin heat out light, in accordance with Beechcraft Service Instructions 0230-412, Rev. II, or later approved revisions.

D) When Paragraph C is accomplished the temporary placard specified in Paragraph A and temporary sealing of aft fuselage door specified in Paragraph B) 7.c. may be removed.

E) Any equivalent method of compliance with this AD must be approvedby the Chief, Engineering and Manufacturing Branch, FAA, Central Region.

This amendment becomes effective April 17, 1975.