AAI's Aerosonde unmanned air vehicle is suffering engine problems that have caused the loss of several aircraft involved with the US Navy's intelligence, surveillance and reconnaissance services contract.

"We have run into what I believe is a number of different issues associated with the propulsion system on that aircraft," Scott Donnelly, chief executive of parent company Textron, told analysts, "and so we were losing more aircraft than we had in our plan."

Textron also owns engine provider Lycoming, personnel from which are involved in investigating the problems.

While aircraft have been lost, they are contractor-owned and contractor-operated. The terms of the US Navy contract stipulate only that a certain number of flight hours be met.

"In fact, our operational tempo remains on track and we are meeting our sensor hour contractual obligations," Textron writes in an email to Flightglobal.

The company declines to provide further specifics, citing operational security, but adds: "We are seeing improvements in the field with notably fewer incidents.

"As with any complex system, issues tend to be interrelated, so we are digging down level by level," Textron says. "Aggressive root cause analysis is enabling us to identify and mitigate issues quickly and effectively."

The Aerosonde is currently being offered in association with EADS company Cassidian to meet an urgent operational requirement for the UK Royal Navy, for which it is facing competition from the Boeing/Insitu ScanEagle.

Source: Flight International