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May 29, 2014 M250--C47 Series CEB--73--6060

E2014 Rolls--Royce Corporation

ENGINE, FUEL AND CONTROL -- NEW ECU SOFTWARE

1. PLANNING INFORMATION

A. Effectivity

(1) Engines

All Rolls-Royce M250--C47B series engines with the following ECUs installed:

C47B

230804902308848423088856

(2) Spares -- Not affected

B. Reason

The new software addresses the power--up faults and overspeed shutdown test disable whichwere introduced with the adapter installed via CEB--A--73--6059.

C. Description

Installation of the false overspeed trip (FOST) adapter (M250--10684) generates power--up faults. Italso makes the overspeed test function inoperable. With this software update, the engineoperation will be restored to normal operation prior to the adapter install. The new software will alsoprovide confirmation that the adapter is installed. It will generate a fault if the adapter is NOTinstalled.

The following software changes are incorporated into this software version:

(1) Change the overspeed protection logic to accommodate the FOST adapter, (M250--10684).The software will now check for the presence of the adapter and declare faults (OSCnfigFlt andOSFlt) if adapter is not detected. The overspeed shutdown test will now function with theadapter installed.

(2) Improvement in the NG Fault detection including eliminating nuisance faults on shutdown.

(3) Added fault detection on starter circuit to check for a stuck on condition.

(4) Improvement in Incident recorder detection logic.

(5) Improvement in the igniter circuit fault detection logic.

(6) Elimination of nuisance Watch Dog Timer faults in the reversionary governor.

(7) Improvement in the primary to reversionary governor hand--off logic.

For C47M operators, new software is planned to make the above changes. This bulletin will berevised at that time to include the C47M part numbers and compliance information.

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