Csl 1082

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TECHNICAL ASPE:CTS ARE FAA APPROVED

LUBRICATION SYSTEM TROUBLESHOOTING

FORWARD:

This Commercial Service Letter is intended to supplement existing instructions and information

contained in the applicable Model 250 Operation and Maintenance Manual, Commercial Service

Letters, and the Airframe Manufacturer’s Instructions. This letter is intended to highlight typ ical

operational discrepancies and provide suggested correc tive action and/or trwbleshooting tips. The

information contaIned herein is ~ all inclusive and further reference to the ;applicable engine/airframe

publications is recommended.

1. OIL SYSTEM SERVICING:

A list of approved oil is contained in the applicable Model 250 Operation and Maintenance Manual.

Instructions contained in the Operation and Maintenance Manual regarding drain intervals,

changing of oil types and the emergency mixing of oils of different groups should be closely

followed. In addition to the instructions conlained in the applicable engine/airframe publications thefollowing suggestions apply:

A. Check the engine oil quantity within 15 minutes of engine shutdow to avoid a false Indication

of excessive oil consumption. If the 15 minutes has been exceeded. motor the engine for 30

seconds with the starter before checking tank quantity. Motoring normally scavenges oil from

the gearbox back to the aircraft oil tank. Check the airframe flight manual; some ins tallations

may require engine to be operated for at least a minute at ground idle to assure proper

scavenging of the engine gearbox.

f&X& Always refer to the Airframe Flight Manual for proper oil servic ing inst ructions.

Spec ific requirements may vary for different aircraft models.

This will scavenge accumulated oil from the gearbox. Recheck the 011 evel after motoring. If

the oil level in the tank increased, it may be indicative that:

(1) The engine oil system check valve in the engine oil filter housing is leaking allowing oil to

drain into the gearbox.

(2) The airframe scavenge check valve (some installations) may be leaking allowing oil to

drain into the gearbox.

(3) An internal oil transfer tube O-ring may be damaged allowing 3il to leak into the gearbox.

(4) Thoroughly agitate the oil in the can prior to adding oil to the s/stem either at an 011

change or during routine servicing .

&QX: Nearly all present day oils contain antifoam additives which can settle to the

bottom of the can. Agita ting the can, and if poss ible, opening the bottom of the

can wil l ensure the additive is uniformly dispersed to the oil.

June 7, 1979

Revision No. 5

March 15. 1997

I

250-Cl8 Series

250-CZO Series

250-C28 Series

25O&C30 Series

250~C2OR Series

250-C40 Series

250-C47 Series

250-815 Series

250-817 Series

250-B17F Series

CSL 99

CSL 1082

CSL 2012

CSL 3011

CSL 4048

CSL 5001

CSL 6021

TP CSL39

TP CSL 1050

TP CSL2032

Page 1 of 4

Rolls-Royce Proprietary Data – Uncontrolled Printed Copy

7/29/2019 Csl 1082


Allison Engine Company

COMMERCIAL SERVICE LEXER

1. OIL SYST EM SERVICING: (c&r@

&!Q!Z Slight wisps of smoke during or after shutdown may be noticed on new or

newly overhauled engines. This is considered normal providing oil

consumption limits are not exceeded AND THERE IS NO PUDDLING IN THE

EXHAUST COLLECTOR.

2. OILCONSUMPTION AND/OR SMOKING:

The applicable Operation and Maintenance Manual contains oil consumption limi ts for all Model

250 engines. Provided the consumption remains at or below these limits the engine should be

considered satisfac tory for continued operation as allowed by the Operation and Maintenance

Manual. Oil consumption in excess of these limi ts should be investigated and corrected.

A. External Oil Leaks:

(1) Visuall y inspect ail engine and airframe oil system components and plumbing for

evidence of oil leakage. It may be necessary to clean the engine/compound with solvent

to determine the source of the leak. The use of aerosol cans of powdered “leak detector’

(Spotcheck Formula “B” Developer, type SKD-NF manufactured by Magnaflux

Corporation, Chicago, Illinois 60656. or equivalent) may prove useful in pinpointing

leaks. Particular attention should be paid to:

(a) Fittings

(b) Oil coolers

(c) Oil tanks.

(2) Visuall y inspect the engine gearbox for evidence of oil leakage. Particular attention

should be paid to:

(a) Splitlines

(b) Compressor mounting inserts

(c) Accessory drive pads and seal drains

(d) Torquemeter support shaft seal

(e) Gearbox fittings.

6. Internal Oil Leaks:

Internal oil leakage is usually manifested as excessive smoking. either continuously or during

engine shutdown.

(1) Number 1 Bearing Seal:

Leakage of this seal will typically result in an excessively dirty compressor and/or oil

venting from the bleed valve. Oil deposited on the compressor blades wil l attract and

accumulate dirt As the accumulation becomes excessive compressor efficiency

deteriorates resulting in complaints of low power. A compressor cleaning wil l usually

restore com pressor efficiency and power for a short interval.

June 7.1979

Revision No. 5

March 15, 1997

250-Cl8 Series CSL 99

250-CZO Series CSL 1082

250-C28 Series CSL 2012


250-C20R Series CSL 4048



250-B15 Series TP CSL39

250-817 Series TP CSL 1050

250-B17F Series TP CSL2032

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COMMERCIAL SERVICE LETTER

2. OIL CONSUMPTION AND/OR SMOKING: (Cont)

(2) Air -Oi l Separator Gear/Vent Lip Seal:

Damage or wear of this seal can result in excessive overboard oil venting.

(3) Worn Turbine Labyrinth Seals:

Excessive clearances of these seals can result in oil entering the gas flow path. This is

usually manifested by continuous smoke durlrig operation and an oil wetted exhaust

collector.

(4) Number 5 Bearing Carbon Be llows Seal:

Leakage of this seal is usually manifested by smoking on shutdown and oil puddling in

the bottom of the exhaust collecto r. (250~C28/C30 exhaust collec tors have overboard

drains, so puddling may not always be evtdent.)

(5) Coke Buildup:

Excess ive oil consumption has been attributed to excessive coke accumulation in the

Number 6 and 7 bearing external sump and/or scavenge strut. This can cause a

restriction to scavenge oil flow resulting in oil entering the gas flow path.

(6) Inefficient O il Pump Scavenging:

Puddling of oil in engine gas flow path, oil running from combustion case drain after

shutdown or smoking during start or shutdown have been attributed to inefficient oil pump

scavenging. Perform turbine sump scavenge check. Check gearbox and atrframe oil

systems tar:

(a) Cut or worn oil transfer lube O-rings

(b) Loose pump mounting screws

(c) Worn transfer tube bores

(d) Blocked oil pump common cavity vent

(e) Excessive oil pump element end clearances

(f) Restrictions in airframe oil tank, cooler or lines.(7) High Gearbox Pressures:

Excess ive gearbox pressures due to a variety of reasons can c:ause high oil consumption

either by overboard venting or by oil bypassing the labyrinth seals into the gas flow path.

Poss ible causes of high gearbox pressures could be:

(a) Restrictions in oil breather vent lines

(b) Improper labyrinth seal clearances

(c) Power Turbine Coupling Bearing Inner Race: This part m’&t have an interference fit

where it mates with the internal seal surface of the power turbine shaft. Leakage of

this seal is virtua lly undetected and should be cowderec! only after all other

possibilities have been exhausted and oil consumption lirnits are sti ll exceeded.

June 7, 1979

Revision No. 5

March 15. 1997

25O&C18 Series CSL 99

250-c20 SerE?s CSL 1082

250-C28 Series CSL 2012250-c30 Series CSL 3011

250-C20R Series CSL 4048



250-815 Series TP CSL39

250-817 Series TP CSL 1050

250-B17F Series TP CSL2032

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COMMERCIAL SERVICE LETTER

3. OIL PRESSURE FLUCTUATIONS:

Exclud ing malfunction in the aircraft ind ication system, fluctuations in oil pressure may be the result

of a number of factors, either singly or compounding one another. The most probable cause ofaeration of the oil (oil foaming), can be any of the following:

A. Damaged O-rings on the internal oil transfer scavenge tubes. This permits excessive air to

be ingested into the oil system.

B. Excessive clearances/leakage of the oil pump

C. Loose oil pump hold down screws

D. Lack of/loss of antifoam additives in the oil

NOTE: Ensure the can is agitated prior to servic ing the system with oil.

E. Low oil supply level

F. Correct oil supply with evidence of foaming after shut down.

G. Review the aircraft engine oil system for configuration and condition per the appropriate

airframe manual.

NOTE: Most aircraft equipped with a wet line oil indicating system utilize some type oforificei restrlctor in the sensing line to provide a stable pressure indication. Systems

employing a transducer with an elec trical ly driven gage dampen the signal

electron ically. Confirm that whichever system IS installed is of the proper

configuration and functions per the manufacturer’s requirements. It is not

uncommon for oil pressure gage “needle bounce” of 3 to 5 psig to be encountered

with some indicating systems.

Inspection of oil filter inlet tube assembly, Model 250 Series I and II engines only. Reference applicable

CEB (Cl8 CEB 274, C20 CEB 1307, C20R CEB 72-4052,815 TP CEB 149.817 TP CEB 1268, B17F

TP CEB 72-2041). Short oil tube resulting in lack of proper engagement into the oil filter housing.

As stated initial ly, this CSL is intended to highlight typ ical oil system operational discrepancies primarily

from an engine point of view. Operators are urged to consult applicab le engine/airframe publications for

more detailed troubleshooting procedures and operator level maintenance actions. Corrective action formany of the discrepancies described in this CSL are contained in the applicable engine Operation and

Maintenance Manual. Operators are encouraged to contact Allison Engine Company, through the

worldwide distributor network, for assistance in troubleshooting and correcting oil system discrepancies.

June 7.1979

Revision No. 5

March 15, 1997

CUSTOMER SUPPORT

ALLISON ENGINE COMPANY

250-Cl8 Series

250-C20 Series

250-C28 Series

250-C30 Series

250-C20R Series

250-C40 Series

250-C47 Series

250-815 Series

250-Bi 7 Series

250-B17F Series

CSL 99

CSL 1082

CSL 2012

CSL 3011

CSL 4048

CSL 5001

CSL 6021

TP CSL39

TP CSL 1050

TP CSL2032

Page 4 of 4


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Csl 1082