Recently, I have experienced an increase in the number of inquiries about the AHRS system in the Learjet 31A. Between Service Bulletin (SB) 31-34-9, the Illustrated Parts Catalog (IPC) 34-24-11 and the Aircraft Maintenance Manual (AMM) 34-28-00, there are numerous errors.
Learjet 31-035 thru -184
This Service Bulletin is NEITHER APPLICABLE NOR APPROVED for EASA Certified Aircraft.
Learjet 31-185 & Subsequent
FYI, the Compass Swing procedure in the MM is incorrect also in regards to the effectivities do not address SB 31-34-9. There is no callout if LCR-100s have been installed.
With this being said, LCR-88s will only be supported for repairs as long as the current inventory of parts exists. Once these parts are depleted, there will be no repairs for LCR-88s. At that point, the only option currently available is to comply with Service Bulletin 31-34-9.
LCR-93s are being supported for repairs. This is why there is no current certification plan to install the LCR-100s in aircraft that currently have the LCR-93s installed.
LCR-100s are still being produced and repairs are still currently being supported.
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