Learjet 25D Job

I got an opportunity to help my brother work on a Learjet 25D yesterday.  This aircraft was produced in 1980, so it is 34 years old, and still a very impressive piece of machinery.  It has had some upgrades over the years, which includes Garmin navigational equipment, and Doppler Radar.  It's beyond my descriptive capability, but a cool ship none the less...

My brother does Altimeter and Transponder Certifications for General Aviation Aircraft, which is an annual process.  Every aircraft has to have their Altimeters, and Transponders certified on an annual basis to make sure that they work within the specifications to maintain flight safety.  He describes this job as routine, and perhaps even boring, but for me it was very exciting to work on one of these awesome machines.

This particular aircraft is a Learjet 25D, and it has two main Altimeters, and one standby Altimeter.  There are also two Transponders, which communicate the aircraft's ID, and altitude to the ground traffic control computers.  There are a large number of sophisticated instruments in the cockpit, all of which have redundant backups, as well as two Cockpit Display Systems, which are digital computers that summarize all of the sensor data that the aircraft generates.  The cockpit is rather small, but has every possible control within reach of the pilot.

This aircraft is parked for extensive maintenance so they have all the access hatches open, and the cowlings have been removed from the engine nacelles.  This is an older aircraft so it has Turbojet engines.  These are relatively inefficient compared with modern technology Turbofan engines, but they still produce huge power, about 3000 pounds of thrust.  Here is a wiki for the Learjet 25.  This was a really neat experience for me, and hopefully it will lead to more of the same...