TB 1-1520-240-20-85
f. Component/Parts in Stock at All Levels (Depot and Others) Including War Reserves - Upon receipt of this TB the
materiel condition tags of all upper boost actuators in all condition codes listed in paragraph 6 below shall be annotated
to read "TB 1-1520-240-20-85, One Time Visual and Records Inspection of the Upper Boost Actuators Not Complied
With". No action required on swashplates.
(1) Wholesale Stock - Upper Boost Actuators Located in All Wholesale Depots Including All Satellite Wholesale Depots
and War Reserve Depots - Report receipt of this TB in accordance with paragraph 14c(1). Upon receipt of this TB depot
commanders and others maintaining wholesale stock shall ensure that serviceable materiel (condition codes "A", "B", and
"C" is placed in condition code 'J" and tagged with a suspended tag/label - materiel DD Form 1576/1576-1. Annotate the
remarks block with " B 1-1520-240-20-85, Project Code XB9, One Time Inspection of the Upper Boost Actuators
T
Required."
(2) Retail Stock - Upper Boost Actuators Located in Installation/Unit Storage - Report receipt of this TB in
accordance with paragraph 14c(2) Upon receipt of this TB, commanders and others maintaining retail stock shall contact
the support aviation organization to perform the inspection required by paragraph 8 and to perform the correction
procedures of paragraph 9 on discrepant materiel. Actuators that indicate overhaul shall be placed in condition code "D"
annotate tag with TB 1-1520-240-20-85, Project Code XB9, One Time Inspection of the Upper Boost Actuators Not
Complied With, and returned to depot for rework. Report compliance with this TB in accordance with paragraph 14c(2).
g. Components/Parts in Work - Upper boost actuators listed in paragraph 6 will not be issued until compliance with
this TB.
2.
Task/Inspection Suspense Date - 10 hours or 14 days whichever occurs first.
3.
Reporting Compliance Suspense Date - No later than 19 July 1996 per paragraph 14a of this TB.
4.
Summary of the Problem.
a. An analysis of a CH-47D aircraft which experienced unexplained control binding has identified two potential
flight control problems The first problem is an out of adjustment condition on upper dual boost actuators overhauled at
Corpus Chnstl Army Depot (CCAD), and the second problem involves swashplate binding due to increased friction.
b. The primary problems with the CCAD overhauled actuators include control valve out of adjustment condition
and the condition of the actuator control valve retainer ring.
(1) The potential problem with the control valve out of adjustment condition is that parked blade loads could
react through the housing of the control valve rather than through the flight control linkage. This condition could lead to a
failure of the internal components of the valve housing.
(2) The second potential problem with the actuators involves the retaining ring used in the actuators control
valve. If the retaining ring is yielded or sprung open during installation, it is possible that the inner sleeve of the control
valve will not reset after secondary valve operation. Secondary valve operation can occur under certain parked blade
load conditions.
c. The problem with the flight controls swashplates binding is the result of increased friction on the uniball which
may cause wear, binding, and scoring of the uniball.
d. For Manpower/Downtime and Funding Impacts - See paragraph 12.
e. The purpose of this TB is to Inspect/perform a one time records check to identify of the upper boost actuators
(P/N 145H6600 and 145H6700) that have been overhauled by CCAD, assign a maximum of 12 months operating time
for CCAD overhauled actuators from the date of this TB, to conduct a forward and aft swashplate pull/friction test, and to
require upper boost actuator blocks, P/N 114E5900-17, be installed anytime the hydraulic power is off for aircraft that
have one or more overhauled actuators installed. The swashplate discrepancies will be repaired as necessary in
accordance with TM or returned to depot.
f. All aircraft that have one or more overhauled actuators installed must have upper boost actuator blocks, P/N
114E5900-17, installed anytime the hydraulic power is off.
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