New FAA Airworthiness Directive Targets Some CRJ & E170 Engines

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New FAA Airworthiness Directive Targets Some CRJ & E170 Engines

BY JAKE HARDIMANPUBLISHED 3 HOURS AGO

The directive specifically concerns turbofans manufactured by General Electric.

The Federal Aviation Administration (FAA), a branch of the United States Department of Transportation, has issued an airworthiness directive regarding certain models of General Electric turbofans. The engines in question are typically found on Bombardier CRJ regional jets, and the Embraer E170 and E175. Let's take a look.

 

The FAA has scheduled to publish the airworthiness directive (AD) in question on April 14th. It has issued the legislation following reports of corrosion in one of the targeted engines, which led to an aircraft's crew receiving an 'Engine Degraded' message inflight. It will come into effect 15 days after its publication, so April 29th.

The particular models of engine that will be subjected to the directive are General Electric's CF34-8C and CF34-8E models. The former sees use on the Bombardier CRJ700, -900, and -1000 series, while the Embraer E170 and E175 models use the latter design. With both types being popular among US regional carriers, this could have significant knock-on effects on airline operations in the country.

So what exactly will the directive require to happen with the targeted engines? Firstly, it demands "a rotational torque check on the actuating linkage assembly." Depending on the results of this test, which must be reported to General Electric, "the compressor inlet guide vane (IGV), outer shroud bushing, and vane spindle bushing" may also need to be replaced. So why is this coming into place?

Several corrosion incidents

The FAA mentions multiple corrosion-based incidents in its report, dating back to last summer. The first of these involved a Bombardier CRJ1000 that had to divert in August 2021 after experiencing an inflight engine shutdown. An investigation found that the corrosion that had caused the shutdown stemmed from the fact that the aircraft had been parked outdoors 10 miles (16 km) from a saltwater coastline.

It wasn't just the location of the parking that had led to the issue, but also the fact that it had spent several extended periods of storage in this condition. Of course, the impacts of the ongoing coronavirus pandemic in the last two years have forced more aircraft into storage than would otherwise have been the case.

The FAA also mentions two other incidents that unfolded under similar circumstances, which occurred in September and October 2021. In both instances, Bombardier CRJ900s with CF34-8C5 engines received inflight engine degradation warnings, with subsequent investigations showing that infrequent use and storage within 45 miles (72 km) of a saltwater coastline had been contributing factors.

Preventing worse occurrences down the line

While the corrosion is yet to result in a major disaster, the FAA is looking to reduce the chances of this with the directive before any such accident can occur. After all, it explains that such degradation has the potential to set off a chain of events that could potentially cause pilots to lose control of their aircraft. But how exactly?

The reason is that, when corrosion reaches a point that it triggers 'Engine Degraded' warnings, software idles the engine, requiring a shutdown and restart to occur. The FAA concludes that "this condition, if not addressed, could result in failure of one or more engines, loss of engine thrust control, and reduced control of the airplane."