Perhaps this?

USE [test]
go

select
    ComponentId,
    partRefId = MIN(partRefId),
    Name,
    DocumentId,
    SheetRef = MIN(SheetRef),
    LocationId,
    Effectivity,
    EffectivityId,
    DesignatorPrefix,
    Designator,
    DesignatorSuffix
FROM PartRef pr
JOIN PartDef pd
ON pd.PartDefId = pr.PartDefId
Where pd.PartClass = 'Component' AND pr.EffectivityId = '11'
group by
    ComponentId,
    Name,
    DocumentId,
    LocationId,
    Effectivity,
    EffectivityId,
    DesignatorPrefix,
    Designator,
    DesignatorSuffix