A newly-revealed plan to re-do one certification test on the G500 business jet won’t cause any further delay for airworthiness approval expected later this summer, Gulfstream tells FlightGlobal.

Gulfstream wrapped up a three-year flight test campaign for the G500 earlier this month and submitted the documentation to the US Federal Aviation Administration for review.

But the programme isn’t done with all certification testing yet.

A petition filed on 20 June by Gulfstream with the FAA asks for a temporary exemption from one of agency’s airworthiness certification rules.

The FAA requires manufacturers to demonstrate that a firewall between the engine and other structures shows no sign of residual burning after being exposed to flames for 15min.

Gulfstream had performed that test on the G500, but the test article lacked a required sealant on top of the fasteners for the firewall attachment flanges.

“The original test to demonstrate compliance was performed with the fire blanket installed; however, the sealant fastener caps were absent,” Gulfstream writes in the petition. “Therefore, [the test article] did not strictly follow the guidance that was provided to Gulfstream by the FAA relative to fire tests.”

Gulfstream plans to re-do the test with the sealant on the fasteners within 90 days after the FAA approves the G500’s type certification.

But the company has asked the FAA for a two-year exemption to the flame exposure rule. It needs the extra time in the “unforeseen” circumstance that the re-do of the certification test leads to a redesign of the firewall, the company’s petition sates.

Gulfstream also asks the FAA to apply the same exemption to the G600, the stretched version of the G500 also scheduled to enter service by the end of the year.

The FAA routinely grants time-limited exemptions to manufacturers that provide a plan complete any missing test data, but each petition is decided on a case-by-casis basis.

Source: FlightGlobal.com