TM 1-1520-238-T-4
6–16
6–7.
SYSTEM DESCRIPTION (cont)
6–7
ENGINE
NGB
ASSEMBLY
ENGINE 2
ACCESSORY
GEAR
TRAIN
MAIN
TRANSMISSION
ASSEMBLY
INPUT DRIVE SHAFT 2
APU DRIVE SHAFT 7
IGB ASSEMBLY
TGB
ASSEMBLY
TAIL ROTOR HEAD
ASSEMBLY
DRIVE
SHAFT 3
ENGINE
NGB
ASSEMBLY
ENGINE 1
APU
DRIVE
SHAFT 4
DRIVE
SHAFT 6
DRIVE
SHAFT 5
MAIN ROTOR
DRIVE SHAFT
INPUT
DRIVE SHAFT 1
MAIN
ROTOR
HEAD
ASSEMBLY
M58-277
ANTI-FLAIL
Figure 6–9.
Drive System Functional Block Diagram
(5) Engine NGB Assembly.
The Engine NGB assembly (fig. 6–10) drives the main transmission through
input drive shafts 1 and 2 while changing the drive angle 90. When the engine is operating at 100%, the engine
NGB assembly reduces engine output from 20,952 to 9,841 rpm.
(a) The oil pump assembly sprays non–filtered oil on the bearing and felt wicking discs in the engine
NGB assembly.
(b) The oil pressure switch monitors oil system pressure during engine NGB operation. When engine
NGB oil pressure exceeds 45 psi and increasing, the oil pressure switch turns off the OIL PSI NOSE GRBX 1 or 2
indicator on the pilot caution/warning panel and the ENG 1 or 2 indicator on the CPG caution/warning panel.
When NGB oil pressure drops within 30–26 psi and decreasing, the indicators light.
(c) The oil filter removes impurities from the oil and has an impending bypass indicator which visually
warns of pressure differential problems in the oil filter, and bypasses oil around the filter when required. An
impending bypass indicator pops out, providing visual indication, when a differential pressure across the filter is
greater than 23 2 psid. If the oil filter becomes clogged, a bypass valve opens to allow the oil to bypass the filter
when 38 4 psid has been exceeded.
(d) The chip detector/temperature switch senses the presence of large metal chips in the oil and
monitors oil temperature. The detector senses the presence of large metal particles in the gearbox oil and causes
the pilot caution/warning panel CHIPS NOSE GRBX 1 or 2 indicators to light. A capacitor discharges to burn off
any accumulation of small metal particles (fuzz suppression) without causing the pilot caution/warning panel
CHIPS NOSE GRBX 1 or 2 indicators to light.
