What Could Cause a Double Engine Failure?

Why Would Both Engines Fail on a Passenger Jet?

Why would all the Engines Fail on a Commercial Passenger Jet?

A look at the reasons that a passenger aircraft’s engines might fail . . .

Why would all the engines fail on a passenger jet?

Any engine failure on a passenger jet is a very rare occurrence and a double engine failure is unbelievably unlikely. You’d actually be more likely to win the lottery! However, despite it being an extremely rare event, it has happened a few times – a famous example being the ‘miracle on the Hudson’.

But what could cause it? Well, bird strikes, fuel starvation, fuel leaks and engine damage could all potentially cause an aircraft’s engines to shut down.

If a plane loses all its engines at a typical crusing altitude of 36,000 feet (which is 6 miles up), it won’t fall out the sky, infact it can still glide for a distance of around 60 miles.

Here are some of the factors which have caused double engine failures in the past:

Bird Strike

Birds can be very hazardous to aircraft. Flying through a flock of geese caused both engines to fail on US Airways Flight 1549 in 2009 that subsequently landed in the Hudson river in New York. A similar incident occurred in 2008 when a flight suffered around 90 individual bird strikes when flying through a flock of starlings on final approach into Rome Ciampino airport. Despite losing both the 737’s engines, the crew managed to land the aircraft on the runway. The aircraft was written off. There isn’t much a pilot can do to avoid birds other than try to manoeuvre the aircraft around them, but they are often seen too late to attempt this.

Shutting down the wrong engine

It sounds difficult to believe, but it has happened. When there has been a problem with an engine, there have been examples of the pilots shutting down the wrong engine (the good engine!), leaving the aircraft without a running engine.

A famous example of this was the British Midland Flight 92 crash at Kegworth where 47 people died. Airlines have updated their procedures as a result and the engine shutdown process is now carefully monitored by both pilots.

Fuel Starvation

A fuel leak or running out of fuel will cause both engines to fail. Air Transat 236 ran out of fuel due to a leak approximately 65 miles from the Azores in 2001. The pilots successfully managed to glide the aircraft to an airbase on the island. In 1983 Air Canada Flight 143 also ran out of fuel when descending through 35,000 feet, due to a fuel miscalculation (the weight of the fuel was measured in pounds instead of kilograms). The pilots successfully managed to glide the aircraft to safety onto a closed runway.

Fuel Icing

Icing in the fuel tanks could stop the engines from receiving fuel. This happened to flight BA38 in 2008 when ice in the fuel lines caused a dual engine flame out on final approach into London Heathrow. This was found to have been caused due to an issue with the Boeing 777 fuel system. The quick actions of the Captain in making the decision to retract some of the flaps reduced the drag of aircraft, allowing the aircraft to clear the airport perimeter fence which saved everyone on board.

Flame Out

An engine works by mixing air and fuel, and then igniting the fuel which produces thrust. An engine flamout is where the ignition of the fuel inside the engine stops. If the fuel isn’t being ignited, the engine won’t be able to produce thrust. An engine flame out on a commerical aeroplane could occur in extreme turbulence or when flying in extremely very heavy rain / precipitation. However, you can normally restart an engine which has flamed out and the pilots would always try and avoid any areas of such extreme rain or turbulence.

Volcanic Ash

Volcanic ash can damage the aircraft’s engines to the point that they flame out or stop the combustion process. In 1982, a Boeing 747, lost all four of its engines due to ingesting volcanic ash. The aircraft glided outside of the ash cloud and managed to restart its engines before successfully landing in Jakarta.

Volcanic ash charts and forecasts have been significantly improved in recent years, so pilots and air traffic control are aware of areas of volcanic ash and can actively avoid them.

Engine Separation

Believe it or not, there is a checklist onboard commercial aircraft in case the engine is separated (comes off!) the wing. The engine is held onto the wing by a ‘sheer pin’ to ensure that the engine separates and protects the aircraft structure if the engine suffers a significant impact.