Butler National Corporation has received FAA supplemental type certificate approval of a replacement two-inch standby altimeter and separate standby attitude indicator into the Learjet 24, 24B/D/E/F, 25, 25B/C/D/F, 28, 29, 31, 31A, 35, 35A, C-21A, 36, 36A, 55, 55B, 55C and 60 aircraft.

The FAA STC approval, number ST00138DE, authorises the replacement of either or both of the two-inch standby altimeter or two-inch standby attitude indicators installed in most legacy Learjet aircraft. The Avcon Industries/Butler Avionics installation package and kit replaces the previously-installed standby equipment with the Mid-Continent Instruments and Avionics MD23 two-inch digital counter drum encoding altimeter and attitude indicator.

President and CEO Christopher Reedy says: “Butler is pleased to have worked with Mid-Continent Instruments and Avionics to offer the Learjet standby altimeter and standby attitude indicator replacement solutions. We have designed the retrofit installations to minimise customer impact and down time. The replacement digital altimeter conveniently replaces most existing two-inch standby altimeters.

“Our avionics technicians have noticed a growing number of operating challenges with existing RVSM standby altimeters when performing the required continued airworthiness checks. The replacement standby altimeter is a quality and cost-effective replacement solution that provides the RVSM (reduced vertical separation minimum) standby functionality. Similarly, the MD23 two-inch digital attitude indicator provides a great looking LCD display replacement for the ageing mechanical standby attitude indicator. Butler Avionics plans to make available the digital standby altimeter and standby attitude indicator STC packages with installation drawings to avionics shops for support installation worldwide.”

“Customers can cost-effectively install our two-inch digital attitude indicator and altimeter in their aircraft. In most installations there's no need to cut the panel, and minimal bus or wiring change is required,” adds Van Winter, vice president of marketing and aftermarket sales, Mid-Continent Instruments and Avionics. “This upgrade is a great, modern addition to the cockpit, providing smooth, high-resolution graphics and advanced functionality.”