ST488SO
Installation of Butler National 6A VAC/10A ADD Area Navigation System with altitude alerting capabilities that meet requirements of FAR 91.51. Held by Southern Airways Company. Last revised January 28, 1972. System: instruments and avionics.
What it applies to
- Kind of product
- Aircraft
- Design holder
- Learjet Inc.; Learjet Inc.; Learjet Inc.
- Models
- Learjet 25 Series, Learjet 24, Learjet 23
- Type certificates
- A10CE, A10CE, A5CE
- The FAA's record
- On the FAA's site
What an approved modification is
A supplemental type certificate is the FAA's approval of a change to a certified design: a new engine or propeller, avionics, an autopilot, floats, a parachute, a larger fuel tank, an ice-protection kit. The company holding it may sell the kit and the paperwork to owners of the listed models; the modification then becomes part of that aircraft's record. The FAA's list says what was approved and for which models, not how many aircraft carry it.
Source: FAA supplemental type certificates (Dynamic Regulatory System). Register counts from the FAA register of October 20, 2026.