Boeing is warning airlines that fly Next Generation 737s, the -700,-800, and -900 series jets to be aware of engine surges, or oscillation as the plane s climb to their cruising altitude.
Though considered statistically rare, Boeing tells KING 5 News there have been 32 incidents of engine surges, lasting anywhere from 10 seconds to a minute while the fuel flow is at its max rate as planes climb to their cruising altitude.
In one of those incidents, both engines surged simultaneously, making this a safety-of-flight issue. In another case, one engine surged followed by the other, but not at the same time. In all other incidents, the oscillation occurred in only one engine.
The incidents took place over a 5-year period, and appear to be more concentrated in flights on the West Coast. 17 of the incidents involve Alaska Airlines, 14 at a second airline Boeing would not name, and one incident at a third.
Boeing spokesman Mike Tull on the 737 program says Boeing is still trying to find the root cause, which could be fuel. A spokesman for Sea-Tac airport said they're unaware of any issues involving the airport s fuel supply.
The incidents appeared to have stopped in December, after Honeywell and CFM upgraded the software going to the small computer on the engine. Honeywell and CFM make the engines under a joint venture between General Electric and Snecma of France.
How rare are these incidents? Next Generation 737s make 16,000 flights a day world wide. These 32 cases happened across 23 million flights, according to Boeing.
The FAA says it s aware of the issue, but so far has not issued an Airworthiness Directive, which is a sign that the regulator considers the problem a serious safety issue.
The Seattle Times first reported on this story.