AD/R44/20 Main Rotor Swashplate and Tail Rotor Bolts 1/2004
TX
Applicability: Model R44 helicopters.
Requirement: 1. For all R44
and R44 II helicopters except those serial numbers specified in
Requirement 2 of this Directive:
a. Determine if maintenance has been performed after 7 February
2003 on the areas specified in Figure 1 of this Directive, and
determine if any bolt, part number NAS6605-31, shown on Figure 1
has been replaced for any reason.
b. If any bolt has been replaced, or if it is uncertain whether any
bolt has been replaced after 7 February 2003, remove the paint from
the bolt head to reveal the vendor identification marking.
Determine if the bolt vendor identification is 01DO.
(i) If the vendor identification is 01DO, comply with Requirements
3 and 4.
2. The following R44 and R44 II helicopters must comply with
Requirements 3 and
4 of this Directive:
a. Model R44 helicopters, serial numbers 0210, 0565, 0641, 0987 and
1312 through 1349, except 1345 and 1346; and
b. Model R44 II helicopters, serial numbers 10010, 10062, and 10083
through 10212, except 10092, 10173, 10204, 10207, 10210, and
10211.
3. For the helicopters affected by
Requirements 1.b.(i) and 2. of this Directive, accomplish the
following:
a. Visually inspect each bolt for fretting residue under the bolt
head, which indicates a loose, potentially cracked bolt.
b. Apply 10-15 ft-lb (13-20 Nm) torque to each bolt head and verify
no
rotation. See Figure 1 of this Directive.
c. If residue or rotation of the bolt is found, replace each
affected bolt with a serviceable bolt that does not have a
vendor identification marking of 01DO.
4. For the helicopters affected by Requirements 1.b.(i) and 2 of
this Directive, replace each bolt, part number NAS6605-31, that has
vendor identification marking 01DO on the bolt head, with a
serviceable bolt, part number NAS6605-31, that has an alternative
vendor identification marking.
Bolt part number NAS6605-31 with vendor identification marking 01DO
on the bolt head, is not to be installed on any helicopter. Note 2:
FAA Emergency AD 2003-24-51 refers.
Compliance: 1. Before further flight after 3
December 2003.
2. At the times specified in Compliance 3 and 4.
3. Before further flight after 3 December 2003, and thereafter
before first flight of each day of operation.
4. Within 10 hours time in service or before 31 December 2003,
whichever occurs first; after determination of vendor
identification and/or helicopter applicability.
This Airworthiness Directive becomes effective on 3 December
2003.
Background: The FAA received a report of the
failure of the bolt that secures parts of the main rotor swashplate
and attaches the tail rotor blade. Investigation revealed that the
bolt failed due to hydrogen embrittlement. Hydrogen embrittlement
is suspected to have occurred during the cadmium plating process of
an entire batch of bolts, which makes the batch suspect.
NTSB Prelim: Hy-Tek Hurricane HP
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