ECU / HMU / POU slide presentation

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ECU / HMU / POUslide presentation
CW2 Scott Paul Rogers

• ECU LOCKOUT
• discussion

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ECU.. WHATS IT DO?

• Trims the HMU NG governor through the tq motor
  within acceptable engine limits to maintain
  isochronous NP governing. This can be overridden
  ONLY by TGT limiting.
• Exchanges tq signals to provide automatic load
  sharing for multi-engine use.
• Provides signal to the POU for NP overspeed
  protection 106- 1
• Provides cockpit signals, NP, TGT, TQ

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ECU FUNCTIONS, OR CHECK RIDE ANSWERS ?

• Np reference from cockpit
• Overspeed signal to POU (redundant power,TQ
  SIGNAL)
• TGT limiting, 837-849
• Signals to cockpit, TQ, TGT, Np
• History recorder signal
• Isochronous NP governing(will maintain ref.)
• Torque load sharing

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HMU DESCRIPTION

• Mounted on the aft center of the AGB
• Receives filtered fuel through cored passages in
  the AGB
• High pressure vane type pump. Max 832 PSI

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HMU FUNCTIONS

• High Pressure Fuel pumping
• Fuel Flow Metering
• Collective pitch compensation (LDS)
• Acceleration/deceleration flow limiting
• Ng limiting (Governing shutdown)
• Variable geometry positioning
• ECU lockout via the PAS
• Torque motor servo to trim NG governor
• Opens Vapor vent for HMU priming

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POU DESCRIPTION

• The Pressurizing and overspeed unit is mounted on
  the aft, left hand side of the AGB
• 3 outlets. Start fuel manifold, main fuel
  manifold, and overboard drain (bypass during
  overspeed)
• 3 inlets. Fuel through AGB core, P3 air,
  overspeed signal

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POU FUNCTIONS

• Sequences fuel to start fuel manifold (2) 17?
• Sequences fuel to main fuel manifold (12) 23?
• Purges start fuel manifold and nozzles during
  start, and main fuel manifold and nozzles during
  shutdown
• Provides NP overspeed protection when activated
  from the ECU overspeed circuit

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We have discussed the functions of the ECU / HMU
/ POU

• Lets now address
• ECU Lockout

Definition of lockout? Caution?
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• The term LOCKOUT is defined as manual
  control of
• engine RPM while bypassing 700 ECU
• When an engine is controlled with ENG POWER
  CONT lever in LOCKOUT, engine response is much
  faster and TGT limiting system is inoperative.
  Care must be taken not to exceed TGT limits and
  keeping RPM R and RPM 1 and 2 in operating
  range.

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