Eclipse Aviation has announced another delay to delivery of its new very light jet as it struggles to secure a US Federal Aviation Administration certificate of airworthiness for the first production Eclipse 500.

The company has halted the C of A process on aircraft AC1 after an FAA review of its compliance with the processes and procedures used to build and test the aircraft revealed “quality escapes”.

“The FAA did what it was supposed to do,” says Eclipse president and chief executive Vern Raburn. “This is not a build or quality issue, this is a process and testing issue. They were not written comprehensively and clearly.”

Eclipse is rewriting its aircraft build instructions and functional test procedures, and expects the FAA team to return to its Albuquerque, New Mexico plan next week to restart the C of A process for aircraft AC1.

Raburn will not give a new delivery date for the first aircraft, but says Eclipse still expects to deliver 10 this year and 515 next year. More than 30 Eclipse 500s are in various stages of assembly, with aircraft 3 and 4 due to fly this week.

News of the compliance issues emerged in a letter to customers prompted by some questioning why they are being asked to make 60% progress payments on aircraft when deliveries are delayed. Eclipse says the payments, for deliveries due by June next year, are tied to production schedules, which are on track