A look inside an engine test cell

No engine arrives unscheduled at a test stand from the wing or a final assembly line. This facilitates planning of human resources and test stand times or the provision of the equipment needed for the respective tests due to be carried out.

To enable the engineers to verify and test as many engines in the test stand as possible, they keep the rigging to a minimum. For all work on the engine that does not have to be performed directly in the test cell, they use the pre-rigging room. This is usually large enough to allow up to three engines to be rigged up at once.

Behind the gigantic sliding doors at the air duct, bird screens and interceptors, for example for pebble stones—and a sound absorber—are hidden.

In the test cell, it’s not possible for engines to power themselves up using the start-up process. For this reason, compressed air—supplied from starter air tanks—is used to help set the engine running.

The test cell is the centerpiece of every test cell. Connected physically with the thrust measuring bridge and digitally with the test bench software, this is where the actual test run takes place. The acceptance test run for a newly assembled or freshly overhauled engine is usually made up of simulated takeoff, cruising and landing sequences. The test cell is large enough to accommodate the additional infrastructure needed for development test runs, such as firing facilities for hailstones or jets for simulating torrential rain.

Before the exhaust air is released into the environment, it has to pass through a sophisticated system of exhaust filters and sound absorbers.

This is the digital home and nerve center for the test engineers. From here, they control and monitor the tests. A large, bullet-proof window gives them a direct view of the engine.In the future, however, this will be replaced by a digital system using cameras and without an additional window.

Once the engine and test cell are decoupled after the test run, the technicians start the de-rigging process. This promptly frees up the test cell for the next engine.

After final inspection, packing and completion of formalities, a tested engine sets off on its travels again—either back to the airline or directly to the aircraft manufacturer’s final assembly line.

Where engines are tested, kerosene is needed, Jet A-1 fuel to be precise. The tank that supplies the test stands in Munich has a capacity of 100,000 liters.