July 23 (UPI) -- Boeing has acknowledged an anomaly occurred during a recent test of its Starliner spacecraft's launch abort system.
The Starliner is being developed to carry astronauts to the International Space Station. It was originally expected to conduct its first crewed test flight by the end of 2018. However, a report by the U.S. Government Accountability Office issued earlier this month suggested that timeline was unrealistic.
The latest setback suggests GAO was right to predict further delays.
A hot-fire test of the Starliner's launch-abort engines conducted in New Mexico last month looked to be going well, but as Ars Technica reported, an anomaly during engine shutdown led to a propellant leak.
Over the weekend, Boeing issued a statement acknowledging the anomaly. The aerospace company said an investigation had identified the problem and its engineers were "moving forward with corrective action."
NASA and its commercial crew program partners, Boeing and SpaceX, are under pressure to deliver safe and reliable transportation vehicles, capable of taking astronauts to and from ISS, by the end of the next year.
Since NASA retired the shuttle program in 2011, American astronauts have been forced to rely on Russian rockets, but NASA's transportation agreement with Roscosmos ends in early 2020.
Boeing and SpaceX are still aiming to conduct unmanned test flights. Vice President Mike Pence is expected to visit Florida in early August to announce crews for the first commercial crew program missions.