Butler National Corporation has received FAA STC approval of a replacement clock that includes USB-A and USB-C chargers into the Learjet Model 24, 24B/D/E/F, 25, 25B/C/D/F, 28, 29, 31, 31A, 35, 35A, C21A, 36, 36A, 55, 55B, 55C, 60 and 60XR aircraft.

The FAA STC approval, ST00235MC, authorises the replacement of the existing OEM-installed clocks with the Avcon Industries/Butler Avionics-designed installation of the Mid-Continent Instruments and Avionics CH93 series Chronos digital clocks with USB chargers. The installation fits within the same panel location and requires only circuit breaker and wiring changes.

Christopher Reedy, president and CEO, says: "Butler is pleased to have worked with Mid-Continent Instruments and Avionics to offer this very desired USB charging capability in the cockpit. Butler/Avcon has designed this retrofit installation to minimise customer impact and down time. We received interests and requests to provide the new USB charging capabilities for the flight crew. Chronos mechanically installs the same as the existing clock. Butler Avionics will make STC kits available for field installation of the clock with USB chargers. The STC is presently applicable to legacy Learjets and the extension of the applicability to other models will be gauged upon customer interest."

“Chronos is a simple, drop-in replacement for most existing clocks,” adds Van Winter, director of aftermarket sales and support for Mid-Continent Instruments and Avionics. “This cost-effective upgrade adds superior, FAA-approved functionality to the flight deck with minimal impact to the instrument panel.”