Reminder: Collins GPS-4000S Airworthiness Directive

Effectivity: All Learjet aircraft equipped with Collins GPS-4000S receivers

ATA: 34

By: Kevin Ensminger – Learjet Service Engineering

Bombardier would like to remind operators of an active Federal Aviation Administration (FAA) Airworthiness Directive (AD) that is open against all Learjet aircraft equipped with Collins GPS-4000S GPS receivers, part number 822-2189-100.

On April 7, 2021, the FAA published AD 2021-08-07 against part number 822-2189-100 GPS receivers. The effective date of the AD was May 12, 2021. It was prompted by an un-announced GPS vertical position error, which could result in a misleading localizer performance vertical (LPV) glidepath.

If not addressed, this condition could result in a misleading GPS position on an LPV approach with the possibility of controlled flight into terrain (CFIT).

There is also an impending issue with the UTC Time Offset that will affect part number 822-2189-100 at the next GPS constellation update, scheduled for June 11, 2023. This condition is described in Collins SIL GPS-4X00()-19-2, publication 523-0826445. This UTC Time Offset is not part of the AD and is a separate issue that is not considered to affect flight safety.

Operators are required to replace part number 822-2189-100 GPS receiver with another part number unit, such as part number 822-2189-101, within 24 months of the effective date of the AD.

Operators may replace their existing GPS receivers with part number 822-2189-101 per Collins AML STC ST01833WI. Ensure the GPS receivers have been modified to address both the AD and the UTC Time Offset issues.

For further questions, contact the Collins Avionics Support Center at: AvionicsSupport@Collins.com or call 1-319-295-5000. Please be sure to include your aircraft type, GPS model number, GPS part number, serial number and modification status.

Contact your preferred Bombardier Service Center or your Regional Sales Manager to discuss installation of Collins AML STC ST01833WI.