Applicability:
Models 369D, 369E, 369F, 369FF, 500N, or 600N helicopters with
either an MD Helicopter Inc. (MDHI) main rotor blade installed or
modified with Helicopter Technology Company, LLC (HTC),
Supplemental Type Certificate (STC) No. SR09172RC, SR09074RC, or
SR01050LA with an HTC blade installed, as listed below:
Model MDHI blade part No. (P/N) HTC blade P/N HTC STC
369D 369D21100 Basic, -516, -517, -523 500P2100-BSC, -BSC-1
SR09172RC
369E 369D21120-501, -503 500P2100-101, -103 SR09074RC
369F, FF 369D21102 Basic, -503, -517, -523 500P2300-501, -503
SR01050LA 369D21121-501, -503
500N 369D21102-503, -517, -523 500P2300-501, -503 SR01050LA
369D21121-501, -503
600N 369D21102-517, -523 500P2300-501, -503 SR01050LA
369D21121-501, -503
Note: The terms “BSC” and
“Basic” are interchangeable when identifying blades
produced by MDHI and HTC.
Requirement: 1. Determine and record the number
of torque events accumulated on each blade. A torque event (TE) is
the transition to a hover from forward flight or any external lift
operation. Each transition to a hover from forward flight is
recorded as a TE, and any external lift operation is recorded as
two TEs. Forward flight is considered to be flight at any airspeed
(or direction) after attaining translational lift. If you cannot
determine the number of TEs, use 13,720 TEs. Continue to record the
number of TEs accumulated (actual usage) throughout the life of the
blades along with hours time in service. On or before accumulating
an additional 200 TEs or at the end of each day’s operations,
whichever occurs first, record and update the accumulated TEs
total.
2. For each blade that has accumulated 13,720 or more TEs and
750 or more hours time in service, before further flight, unless
already accomplished; and thereafter after at intervals not to
exceed 200 TEs or 35 hours time in service, whichever occurs first,
perform a main rotor blade torque event inspection. If a crack is
found, before further flight, replace the affected blade with a
serviceable blade.
Note 1: MD Helicopters Inc. Maintenance Manual
CSP-HMI-2, Revision 36, Section 62-10-00, paragraph 8, Main Rotor
Blade Torque Event Inspection, pertains to the subject of this
Directive.
Note 2: MDHI Maintenance Manual CSP-HMI-2, Section
20-30-00 Main Rotor Blade Painting, pertains to the subject of this
Directive. This section of the maintenance manual recommends
painting the inboard 24-inches (not to be exceeded) of the blade
gloss white to aid in detecting a crack; and if this is done,
painting all blades alike and rebalancing them.
Note 3: TEs are used only to establish an
additional inspection interval and not to establish an alternate
retirement life.
Compliance: 1.
Within 50 hours time in service after 7 December 2005, unless
already accomplished.
2. As specified in Requirement 2.
This Amendment becomes effective on 7 December 2005.
Background: The FAA required certain actions in
response to several reports, including a recent report dated 24
July 2003, of blade cracks due to a high number of TEs per hour.
The actions specified in this Directive are intended to prevent
fatigue cracking of the blade, blade failure, and subsequent loss
of control of the helicopter.
Amendment 1 is issued in response to a new FAA AD, which revises
model applicability, adds MDHI part-numbered blades, removes any
reference to the life limits of the blades, changes the
requirements for inspecting the blades, and revises the STC
applicability. The FAA AD also provides that compliance with
portions of certain documents constitutes alternative methods of
compliance, contains editorial changes for clarification, and makes
some corrections. The FAA AD was prompted by additional reports of
cracked blades and by comments received in response to FAA AD
2003-24-01.