TB 1-1520-240-20-126
f.
Component/Parts in Stock at All Levels (Depot and Others). N/A.
g. Components/Parts in Work (Depot Level and Others). Items listed in paragraphs 6 and 7 in work
will not be issued until compliance with this Technical Bulletin.
2.
Task/Inspection Suspense Date. Prior to next flight but no later than 5 October 2000.
3.
Reporting Compliance Suspense Date.
Report compliance in
accordance with paragraph 14a no
later
than 13 October 2000.
4.
Summary of the Problem.
a. Modification Work Order (MWO) 1--1520--240--50--83 installs T55--GA--714A engines on the H--47
aircraft. Part of the installation is a P3 signal line from the engine hydro--mechanical assembly (HMA) to the
digital electronic control unit (DECU). This line has a water drain cartridge. The drain cartridge incorporates
a plastic sight tube for detecting water that may accumulate in the line. The plastic sight tubes have not been
stress relieved and minute axial cracks develop easily which can cause P3 air leaks. In primary mode, the
P3 signal is used to calculate a fuel flow limit. If the cartridge leaks, the P3 signal to the DECU may decrease
enough to cause a lowering of fuel flow but not enough to engage the software fault detection logic. This will
result in a partial or complete loss of engine power while in primary mode.
b.
c.
The purpose of this Technical Bulletin is to --
(1) Inspect for defective P3 water drain cartridges.
(2) Replace defective cartridges as required.
5.
End Items to be inspected . All H--47 series aircraft.
Assembly Components to be Inspected.
NOMENCLATURE
PART NUMBER
NATIONAL STOCK NUMBER
FADEC TOP KIT
145PK010-1
Parts to be Inspected .
PART NUMBER
NATIONAL STOCK NUMBER
NOMENCLATURE
DRAIN CARTRIDGE
L84230
Inspection Procedures.
a.
Determine if the aircraft has a FADEC system installed --
(1) If the FADEC system is not installed, the inspection is complete and the red horizontal dash
// -- // entry may be cleared.
(2) If the aircraft is equipped with a FADEC system, proceed to paragraph 8b.
b. Locate the P3 line drain cartridges, part number L84230, TM 55--1520--240--23P--3, Figure 367,
Item 79, and Figure 357, Item 75. There is one on each side of the aft cabin wall at approximately station 490.
(1) If the P3 line drain cartridge has the letter "C" after the serial number, no further action is re-
quired and the red horizontal dash // -- // entry may be cleared.
(2) If there is no "C" after the serial number replace the P3 line drain cartridge in accordance with
Correction Procedures.
a.
Remove the P3 line drain cartridge.
2