Commercial Engine Bulletin: Engine, Turbine Assembly - Steady - State Operation Avoidance Range Limit
Commercial Engine Bulletin: Engine, Turbine Assembly - Steady - State Operation Avoidance Range Limit
Commercial Engine Bulletin: Engine, Turbine Assembly - Steady - State Operation Avoidance Range Limit
A. Effectivity
(1) Engines
All Rolls-Royce Model M250 --C20, --C20R, --B17 and --B17F Series engines are affected
by this Commercial Engine Bulletin (CEB).
(2) Spares -- Not affected
B. Reason
This Alert CEB has been released by Rolls--Royce to heighten awareness of the N2 speed
avoidance range for Series II engines. It is required to observe the speed avoidance range and
operating procedures to minimize the possibility of power turbine failure.The required engine N2
speed avoidance range is dependent upon the part number of the Power Turbine Wheel in
service, engine model, and the OEM application in which the engine is installed. Part numbers
of the 3rd--stage and 4th--stage Turbine Wheels in service, engine models, and the OEM
applications affected are as follows:
(1) Enhanced Power Turbine Fitted with P/N 23065818 3rd--stage Turbine Wheel and P/N
23055944 4th--stage Turbine Wheel or P/N M250--10445 4th--stage Turbine Wheel.
For normal operation, all OEM applications are affected. The engine N2 speed avoidance
range is dependent upon the part number of the 4th--stage Turbine Wheel installed and the
engine model.
(2) Non--Enhanced Power Turbine Fitted with P/N 23065833 3rd--stage Turbine Wheel.
For normal operation, the following OEM applications are affected: Agusta A109 (all
models), Soloy B206L/R and Eurocopter BO105 (all models). In addition, this speed
avoidance range is applicable during One--Engine--Inoperative (OEI) operation of
multi--engine aircraft. P/N 23065833 wheel is no longer manufactured and so alternative
options for replacement of the wheel at next turbine overhaul are discussed in paragraph
2.C.(1)(d).
(3) Non--Enhanced Power Turbine Fitted with P/N 23001967 3rd--stage Turbine Wheel and
P/N 6853279 4th--stage Turbine Wheel.
No N2 speed avoidance range is required for any OEM application. P/N 23001967 and P/N
6853279 wheels are not affected by this CEB and are mentioned only for completeness.