Csl 1034

7/29/2019 Csl 1034

1/8

250-C20 CSL-1034COMMERCIAL SERVICE

Oetmit Diesel AllisonLETTER

Indianapolis. ndiana 46206 Page 1 of 8January 16, 1975FAA-DER ApprovedSubject: CEO0 Fue l Control Flush ing Procedure to Remove SuspectedInternal ContaminationInternal contamination in the fuel control can lead to an array of performanceproblems: hung starts, no start, erratic operation, uncontrollable accelera-tion with no response to adjustment. As a result, the unit is prematurelyremoved and returned to the distributor for corrective action. In manycases, investigations of prematurely removed fuel controls revealed thatcontamination may have been sufficient to affect performance.After reviewing the different operating environments and fuel hand ling technques employed by 250 operators, the most practical approach to the problemis to flush the fuel control with clean, filtered calibrating fluid or engine fuelafter overhaul or removal from storage. In the event of premature removalfrom the aircraft/engine for one of the aforementioned problems, operatorsmay elect to flush the unit or return it to the distributor for corrective actionThe following flushing procedure, therefore, is recommended at

. Operator main tenance facilities or distributor facilities onall mode l MC-40 Fue l Controls, P/L 104000, removed fromservice for suspected contamination or performance pro-blems of hung starts, no start, erratic operation, uncon trol-lable acceleration or hot start with no response to adjustment.0 Distributor facilities on all controls processed for overhaulor after remova l from storage. Purging should be completedprior to preset calibration .

MANPOW ER: It is estimated that approximately 0.5 man-hour will berequired to flush one unit.TOOLING: A test/flushing stand or other fluid supply capab le ofdelivering Calibrating Fluid, MIL-F-7024 Type Il, orengine fuel at 100 psig with a fuel delivery of 350 poundsper hour (phr). Filtration of 10 microns is required.Use holding fixture STD67180 (or equivalent) mountedto flushing stand or equivalent, and Speed Rotor Wrench,STD67229, or equivalent.

Rolls-Royce Proprietary Data Uncontrolled Printed Copy

7/29/2019 Csl 1034

2/8

250-C20 (XL-1034Page 2COMMERCIAL SERVICE LETTER

ACCOMPLISHMENT INSTRUCTIONS:A. Prepare the fuel control forflushing. Refer to Figure 1 for portidentification.

1.

2.

3.4.

5.

Mount control on STD67180 Holding Fixture (or equivalent) securedto flushing stand, plug or cap all open ports and thoroughly washall external surfaces with calibrating fluid or engine fuel. Blowdry with filtered compressed air.Remove the following pressure port plugs or fittings: Pl, BF, SS,FG, AF, BR, AR and Bypass. Remove speed sense rotor groupand SS restriction.NOTE: Do not remove O-rings from port plugs, fittings, andspeed sense rotor group unless damaged.Connect a line (as short as possible) between the Fuel-out to PTGand Fuel-in from PTG ports (see Figure 2).Connect the fluid supply line to the Fuel Control inlet port (seeFigure 2). Put test stand spray shield in place if applicable.NOTE: Calibrating fluid or engine fuel that is flushed throughthe fuel control sha ll not be recirculated or reused forflushing unless it is filtered to 10 microns.On field returned units and units removed from storage, note thelocation of the clip or stop screw in the Start Derichment Adjustmentand position of Light-Off Adjustment (see Figure 3). Temporarilymark the casting boss with the location of the clip or screw on theDerichment Adjustment. Also, put a temprorary scribe mark onthe Light-Off Adjustm ent and Start Flow Adjustment.

B. Flush the fuel control as follows:CAUTION

BESURE THATTHEFUELOUTLETANDBYPASSAREOPEN. COVERTHE FUEL CONTROL WITH A CLEAN PLASTIC BAG TO PROTECTAGAINST FLUID SPRAY.1. Supp ly calibrating fluid or engine fuel to the fuel control inlet asrequired to obtain a steady flow from the open pressure ports(approximately 100 psig at a flow of 325 pounds per hour (phr).


7/29/2019 Csl 1034

3/8

250-c20 CSL-1034Page 3COMMERCIAL SERVICE LETTER

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 Pl pressure port plug.b. Install the SS Restriction and Rotor Group.c. During flushing of the BR and AR ports cycle the start DerichmentAdjustment back and forth through its limit of travel, as re-stricted by clip or stopscrew. Cycle the Light-Off Adjustmentclockwise and counterclockw ise approximately l/4 turn andcycle the Power Lever from Max. to 10 degrees. Install BRpressure port plug.

NOTE: Return the Start Derichment Adjustmen t and Light-Off Adjustmen t to the previously marked positions(refer to paragraph A. 5).d. Jnstall AR pressure port plug.e. Install BF pressure port plug.f. Install SS pressure port plug.g. Install FG pressure port plug.h. Cycle PC pressure ambient to 80 psia. and install AF pressure

port plug.1. Purge through Bypass port.

NOTE: Whenever possible, position the fuel control andholding fixture in such a way as to have purgingfluid directed to test stand sink.C. Completion

1. Disconnect the Fue l Control Inlet Port from the flushing standsupply.2. Install aircraft/engine fittings. Torque all plugs and fittings to

the required specification and lockwire as required.


7/29/2019 Csl 1034

4/8

250-C20 CSL-1034Page 4COMMERCIAL SERVICE LETTER

3. Remove the fuel control from the flushing stand.a. Maintenance units are ready for reinstallation.b. Overhaul units

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

L. 0. DavidsonService ManagerAircraft EnginesMJK/bsc


7/29/2019 Csl 1034

5/8

250-C20 CSL-1034COMMERCIAL SERVICE LETTEgqe 5

FUEL INLET

BY-PA:POR T

AR Pt-6

(5-10 IN.-LB)

Pi10

3R TIN.- -LB!

PORTLOCATIONSFrGuRE (SIIEET~ 0~ 2)Rolls-Royce Proprietary Data Uncontrolled Printed Copy

7/29/2019 Csl 1034

6/8

FG PI3R T(5-10 IN.-L

250-C20 CSL-1034Page6COMMERCIAL SERVICE LETTER

LIGHT-OFFFUEL OUT TO POWER A DJ US TM E NTTURBINE GOVERNOR /

P15

FUEL IN

7/29/2019 Csl 1034

7/8

250-C20 CSL-1034Page7COMMERCIAL SERVICE LETTER

FLUID SUPPLY LINE

PTG BY-PASS LINE

HOLDINGFIXTURESTD67 180

SS RE5TRICTION

-SPEED SENSEROTORGROUP

FLUIDCONNECTIONSFIGURE 2


7/29/2019 Csl 1034

8/8

250-C20 CSL-1034Page 8

COMMERCIAL SERVICE LETTER

LIGHT-OFFADJUSTMEN

CLIP STOP SCREW

ADJUSTMENTSFIGURE 3

Rolls Royce Proprietary Data Uncontrolled Printed Copy

Documents

Csl 1034