History has shown that failure to observe proper safety precautions, such as good communication and awareness of the hazard areas in the vicinity of an operating jet engine, can result in serious injury or death. The risk of ingestion can be prevented with appropriate training and adherence to the safety precautions and hazard areas outlined in the applicable Airplane Maintenance Manual (AMM) chapter 71 procedures. Although this article is written primarily about 737 engine hazard areas, the risk of ingestion exists on all airplane models.
By Fred Zimmer
Lead Engineer, Service Engineering, Propulsion
Airline and airport employees work around commercial airliners every day throughout the world without incident. However, neglecting to stay out of the engine inlet hazard areas or complacency working near operating engines can result in severe injury or death.
There have been 33 reported ingestions of personnel into an engine on 737-100/-200 airplanes since 1969. Several of these ingestions caused serious injuries and one resulted in a fatality. There have also been four reports of fatal ingestion incidents on 737-300/-400/-500 and Next-Generation 737 airplanes. The most recent fatalities occurred in 2006.
This article outlines the importance of avoiding engine inlet hazard areas when working on or near operating engines and provides recommendations for preventing engine ingestion.
THE DANGERS OF ENGINE INGESTION NEAR AIRPLANES
When a jet engine operates, it creates a low-air-pressure area in the inlet. This low-pressure area causes a large quantity of air from the area forward of the inlet cowl to go into the engine. The air that is near the inlet cowl moves at a much higher velocity than air that is farther from the inlet. As a result, the amount of engine suction is small until one nears the inlet, where the suction increases significantly.Because of the dangerous pull of engine suction, it is important for ground personnel working near commercial airliners with operating engines to stay at a safe distance from the forward engine area to avoid the possibility of injury or death. This is particularly important on airplanes with low ground clearance, including the 737. Additionally, there is a much greater potential for serious or fatal injuries if ingestion into a CFM56 engine occurs because the CFM56 does not have inlet guide vanes. The JT8D has 19 stationary inlet guide vanes that have provided ingested personnel some protection from fatal contact with the rotating fan.