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250-c20 (XL-1035COMMERCIAL SERVICE LETTER

h Detroit Diesel Alllison4 Indianapolis. ndiana 46206 Page 1 of 8January 16, 1975FAA-DER Approvedubject: CECO Power Turbine Governor Flushing Procedure to RemoveSuspected Inkrnal Contaminationnternal contamination in the governor can lead to an array of performanceroblems: uncontro llable N2, sluggish response, high power lever torque,rratic operation, or uncompensated N2 droop. As a result, the unit is pre-naturely rem oved and retul ned to the distributor for corrective action. Innany cases, investigations of prematurely removed governors revealed thatontamination may have been sufficient to affect performance.&ter reviewing the different operating environments and fuel hand ling techni-ues, the most practical approach to the problem is to flush the governor withlean, filtered calibrating fluid or engine fuel after overhaul or removal fromtorage. In the event of premature removal from the aircraft/engine for onef the aforementioned problems, operators may elect to flush the unit or re-urn it to the distributor for corrective action.The ollowing flushing procedure, therefore, is recommended at

l Operator maintenance facilities or distributor facilities onall mode l MC-40 Power Turbine Governors, P/L 104100or 104500, removed from service for suspected contamina-tion or performance problems of uncontro llable N2, sluggishresponse, h igh power lever torque, erratic operations, oruncompensated N2 droop.0 Distributor facilities on all governors processed for overhau lor after rem oval from storage. Purging should also be ac-comp lished prior to preset calibration.

IANPOWER: It is estimated that approximately 0.4 man-hour willbe required to flush one unit.OOLING: A Test/Flushing stand or other fluid supply capable ofdelivering Calibrating Fluid, MIL-F-7024, Type II, orengine fuel at 100 psig with a fuel delivery of 350 poundsper hour (phr). Filtrationof 10 microns is required. UseHoldingFixture STD67180 (or equivalent) mounted toflushing stand (or equivalent) and Spee d Rotor W rench,STD67229 (or equivalent).

Rolls-Royce Proprietary Data Uncontrolled Printed Copy

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ACCOMPLISHMENT INSTRUCTIONS:A. Prepare the power turbine governor for flushing. Refer to Figure ! forport identification.

1.

2.

3.

Mount the governor on STD67180 Holding Fixture (or equivalent),secured to flushing stand (see Figure 2). Plug or cap all open portsand thorough ly wash all external surfaces with calibrating fluid oreng ine fuel. Blow dry with dry filtered compressed air.Remove the following pressure port plugs and fittings: BG, SS, AL,AG, PO, Bypass and Speed Set Access Port. Remove the SpeedSense Rotor Group using STD67229 Wrench and the SS restriction.NOTE: Do not remove O-rings from port plugs, fittings, and speed

sense rotor group unless damaged.Connect the Flushing Stand fluid supply line to the Fuel Inlet Port(see Figure 1, sheet 1).NOTE: Calibrating fluid or eng ine fuel that is flushed through thegovernor sha ll not be recirculated or reused for flushingunless it is refiltered to 10 microns or better.

B. Flush the governor as follows:CAUTION

BE SURE THAT THE FUEL OUTLET AND BYP ASS PORTSAREOPEN. COVERTHEGOVERNORWITHACLEANPLASTIC BAG TO PROTECT AGAINST FLUID SPRAY.1. Supply flushing fluid to the Governor Fue l Inlet as required to obtaina steady flow from the open pressure ports (approximately 100 psigat a flow rate of 325 phr).2. Allow each port to purge lo-20 seconds. Install one plug or fittingat a time in the following order, purging between installations.

a. Install SS Restriction and Rotor Group.b. Install BG pressure port plug.


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250-c20 (XL-1035Page 3COMMERCIAL SERVICE LETTER

C.d.

e.

f.

g.h.1.j.

Install SS pressure port plug.Cycle the governor power lever through its travel range whilepurging through the AL port. Install A L pressure port plug.On early Model Governors only, remove AD pressure portplug and Response Lag Jet. Purge and cycle PC pressureambient to 80 psia, if air supply is available. Install ADpressure port plug and Response Lag Jet. On later models,the AD pressure port and Response Lag Jet are eliminated.Purge and cycle PC pressure ambient to 80 psia, if air sup-ply is available. Install AG pressure port plug.Remove the Fixed Orifice located through the Fue l Outlet.Purge md reinstall the Fixed Orifice.Cycle the governor power lever through its travel rangeand install the speed set access cover.Temporarily restrict the Fue l Outlet and Bypass ports.Install the PO pressure port plug.Purge through the Bypass and Fue l Outlet Ports.NOTE: Whenever possible, position the governor an dholding fixture in such a way as to have purgingfluid directed to test stand sink.

C. Completion:1. Disconnect the governor Fue l Inlet Port from the flushing standsupply.2. Install aircraft/engine fittings. Torque all plugs and fittings tothe required specification and lockwire as required.


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250-C20 CSL-1035Page 4COMMERCIAL SERVICE LETTER

3. Remove the governor from the flushing &and.a. Maintenance units are ready for reinstallation,b. Overhaul units

(1) If unit is in process of overhaul, the unit is now ready forPreset Calibration.(2) If overhaul has been completed, final calibration recheckis suggested if practical.

Service ManagerAir craft EnginesMJK/bsc


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~-.5-10 IN.-LB)

PORTLOCATXONSFIGURE i (SHEET i 0~ 3)


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ss PC(5-10

PORT LOCATIONSFIGURE 1 (SHEET 2 OF 3)

IR TIN.-LB)


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AL PORT(5-15 IN.-LB)

FUEL OUTLETFIXEDORIFICE(20 IN.-LB MAX)

EF

AG P15-15

\R~ToR GROUP 120-:30 IN.-LB)AND SS RESTRICTION(20 IN.-LB MAXI(SEE FIGUR E 2)

iE-LB)

* PORTLOCATIONSFIGURE i (SHEET 3 OF 3)


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FIXTURESTD67180

\\

SS RESTRICTION

SPEEDSENSEROTORGROUPFLUIDCONNECTIONFIGURE 2


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Csl 1035