Textron Cessna - Propeller Troubleshooting

McCAULEYPROPELLERSYSTEMS
CONSTANTSPEEDCOMPOSITEOWNER/OPERATOR
INFORMATIONMANUAL
PROPELLERTROUBLESHOOTING
1.GeneralInformation
A.TypesofProblemsNormallyEncountered
(1)Thissectionoutlinesandexplainsanumberofoperatingcharacteristicswhichhavebeen
observedinservice.Thereissomediscussionofpropellerdesignasitrelatestothese
characteristics.Proceduresforlocatingandcorrectingcausesofundesirableoperationare
given.
2.PropellerRPMFluctuations
A.Symptoms:
(1)Huntingisacyclicorconstantvariationofenginespeed,aboveandbelowthatdesired.Itwill
beshownbyconstantwaveringofthetachometerreading.
(2)Surgingisawideorexcessiveincreaseordecreaseinenginespeedfollowedbyreturntothe
establishedspeedafteroneormoreoscillations.
(3)Surgingwilloccurandshouldbeconsiderednormaliflever/throttleismovedrapidly.
B.PossibleCauses:
(1)Huntingisseldom,ifever,causedbythepropelleritself.Thoseconditionsreportedprimarily
havebeencausedbyotherpartsofthesystemsuchasgovernor,fuelcontrol,etc.
(a)Forpistonengineinstallations,thepropellercanbetestedinightbyreducingthemanifold
pressure.ThepropellercontrolshouldbeinthefullRPMpositionandthemanifoldpressure
shouldbereduceduntiltheRPMdropsslightly.Thisensuresthatthepropellerisagainst
itslowpitchstopandiseliminatedfromtheequation.
(2)Surgingmaybecausedbyairinthepropellercontrolhydraulicsystem,governornotoperating
correctly,orproblemsassociatedwiththeenginetransferbearingorcollar.
(3)Ifthegovernortestissatisfactoryandnoothersystemfaultscanbefound,thepropellermaybe
atfault.Althoughveryrare,huntingandsurgingmaybeduetoexcessiveinternalfrictioninthe
propellerorover-shimmingofthepropellerblades.
C.CorrectiveAction:
(1)Ifthepropellerissuspectedasthecause,itshouldberemovedforexaminationbyaMcCauley
authorizedservicefacility.
(2)Surginghasbeenencounteredongroundoperationafterinitialinstallationwhilepurgingairfrom
thesystem.
(a)Ifencounteredatothertimes,thepropellershouldbecycledrepeatedlytoremoveallair
fromthesystem.
(b)Iftheconditionpersists,itmaybeattributabletothegovernor,andthegovernorshould
beremovedandtested.Thepropellershouldbepurgedofairagainafterthegovernoris
reinstalled.
3.ChangingRPMorCreeping
A.PropellerRPMchangingandholdingnewsetting.
(1)PossibleCause:
(a)Excessive"play"inthelinkagebetweenthegovernorandthecockpitcontroloftenleads
toerraticoperation.
(b)Possibleexcessiveenginecompartmentheataffectingthegovernorplastictopcover.
(2)CorrectiveAction:
(a)Tracelinkage,locateunsecuredsections,andtightenasneeded.
(b)Pleasenotethatalthoughlinkagemayappeartoallowfullgovernorcontrolwhiletheengine
isoff,itmaynotintheair.Enginevibrationand"stretch"ofthemountduringoperationcan
oftenaggravatethecondition.Therefore,itisimportanttheentirelengthoflinkagebe
properlysecured.
(c)Ifheathasdistortedtheplastictopcover,replaceitwithanewtopcoveranddetermine
thesourceoftheexcessiveheat.
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©McCauleyPropellerSystemsJan9/2017