Company uses rare S.211 jet as flying test bed for lithium-ion battery

Mid-Continent Instruments and Avionics is using a rare jet trainer as a flight-test platform for its own products, according to comments made at EAA AirVenture 2026 in Oshkosh, Wisconsin.

Company president Matthew Harrah, who is also chief test pilot, displayed an SIAI-Marchetti S.211 alongside the equipment it helps evaluate. The aircraft was built as a trainer for the Singapore and Philippine air forces in the 1980s. About 60 were produced, and roughly a dozen now fly in U.S. civilian hands, most acquired from surplus military inventories, according to the account.

Harrah said the airplane was acquired mainly for testing rather than display. That work includes manoeuvres at high angles of attack, which the company needs to evaluate attitude indicators and other instruments, nearly all of them solid state, he said. Some mechanical components are still supported as well. The goal, he said, was an aircraft reliable and efficient enough to carry out that testing with a greater margin of safety.

Everything in a flight-test programme comes down to managing risk, Harrah said. The company looked for an airplane that would let it conduct its testing without problems.

Central to the installation is a 50 amp-hour lithium-ion main-ship battery from True Blue Power, the Gen5 TB50. It is designed to occupy the same space as the lead-acid batteries long used to start piston and turbine engines, according to the source material.