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Embraer Legacy & Praetor: Honeywell Software Upgrade for Engine Electronic Control Units

October 2020


Honeywell has issued SB (Service Bulletin) AS907-76-9029 Rev 1, dated 29 June 2020, pertaining to a software upgrade for the Engine ECU (Electronic Control Unit) specific to Honeywell AS907-3-1E (HTF7500) engines.

This SB is applicable to the following:

Electronic Control Units

Part number

2119576-4103 to -4104


2119576-4203 to -4204

Or Install




Honeywell Engines

AS907-3-1E (HTF7500) engine


EMB 545/550 (Embraer Legacy 450/500)

EMB 545/550 MOD (Praetor 500/600)

Once this software is upgraded, the ECUs will be reidentified as part number 2119576-4104 and PN 2119576-4204.

Compliance Timing

Honeywell recommends this service bulletin be accomplished at next scheduled engine or airframe maintenance at no charge, but no later than 24 months from the initial publication date of this service bulletin, June 29 2020.

Compliance Guidelines

  • There are two ECUs per engine, with a total of four ECUs per aircraft. All four engine ECUs must be upgraded simultaneously.
  • The SB may be accomplished while the engines are installed.
  • The aircraft will need to be fully operational at the time of the ECU upgrade.
  • ECU part numbers 2119576-4104 and -4204 can be intermixed on the same aircraft.
  • Embraer SB 550-73-0002 Rev 5 Engine and Fuel Control – Engine ECU Software Upgrade Version 5.0, must be complied with concurrently to Honeywell service bulletin AS907-76-9029.

Service Bulletin Background

The software upgrade improves an identified safety issue to avoid unintended engine shutdown, loss of thrust control, increased N2 field margin, enhanced engine fault detection, and enhanced engine systems monitoring. The upgrade will also alleviate nuisance fault codes and nuisance MCID (maintenance condition identification). The new software will assist in troubleshooting and update engine synchronization logic.

The changes will affect many systems including but not limited to N2 speed, TT2 heater circuitry, engine overspeed causing unintended engine shutdown, EGT low temp limits, throttle lever exceedances, and low energy starts.

Service Bulletin Action

As a Honeywell Authorized Service Center with Honeywell trained technicians, Duncan Aviation is authorized to perform Service Bulletin AS907-76-9029.

Warranty Coverage

The software upgrade is free of charge to the operator.