Applicability:
Models AS 355 E helicopters, equipped with main servo-controls, all
part numbers, not modified per MOD 073343, and on which the
tightening torque of the nut that secures the upper ball-end has
been increased following:
- embodiment of MOD 073191; or,
- compliance with MET Work Card 67.30.00.402 since MET Revision
04-08.
Requirement: 1. Check the tapered housings of
the main servo-controls for cracks, in accordance with paragraph
2.B.2.of Eurocopter AS 355 Alert Service Bulletin (ASB) No.
05.00.48.
a. If no crack is evident, comply once with paragraph 2.B.3. of
ASB No. 05.00.48, then resume flights.
b. If there is a vertical crack (along the servo-control axis) that
is less than 20 mm long: (i) Comply once with paragraph 2.B.3. of
ASB No. 05.00.48, and identify the end of the crack using an
indelible ink marker and resume flights.
(ii) Comply with paragraph 2.B.4. of ASB No. 05.00.48.
2. Replace the servo-control in accordance with paragraph 2.A. of
ASB No. 05.00.48, in the following cases if:
- a vertical crack is found (along the servo-control axis) that is
20 mm long or longer,
- the crack has grown by more than 5mm,
- there is an oblique or a horizontal crack,
- there are several cracks.
For main servo-controls held as spares:
3. Accomplish paragraph 2.B.2.b. of ASB No. 05.00.48.
If no crack is evident, comply once with paragraph 2.B.3. of ASB
No. 05.00.48.
If a crack is evident, return the servo-control for repair.
Note: EASA AD 2006-0055-E refers.
Compliance: 1.
Within 10 flight hours or 10 days after 6 March 2006, whichever
occurs first. 1.b.(ii) During the check after the last flight of
the day, without exceeding 10 flight hours between two inspections,
pending replacement of the servo-control (in accordance with
paragraph 2.A. of ASB No. 05.00.48) no later than within 150 flight
hours without exceeding 3 months.
2. Before further flight.
3. Within 10 days after 6 March 2006, or before installing a main
servo-control held
as spares.
This Airworthiness Directive becomes effective on 6 March
2006.
Background: The European Aviation Safety Agency
received reports of cracks discovered in the tapered housings of
main servo-controls during scheduled inspections. Undetected
cracking in the tapered housing of a main servo-control could lead
to the loss of attachment of the affected servo-control to the
non-rotating swashplate, and consequent loss of control of the
helicopter.