Whilst the SAR operations for the passengers and crew of QZ8501 are going on, on 4-1-2015 AirAsia flight QZ7633 from Bandung to Surabaya had engine problems.
THE ENGINE PROBLEM THAT WAS “DOWNPLAYED”.
On 4-1-2015 there was another adverse news about AirAsia’s flight QZ 7633 from Bandung to Surabaya, which was taxiing for two to three minutes preparing for take off and it had to turn back due to engine problems. Of course, this was downplayed as a small matter by non other than the AirAsia’s supremo, Tan Sri Tony Fernandes. He had lashed out against the media for being “silly” and “sensationalising”, HERE.
In November 2012, the Malaysian Department of Civil Aviation (DCA) granted AirAsia a 6 months Air Operation Certificate (AOC) due to its failure to meet safety regulatory standard, HERE.
Below is a well thought out comment and backed up by research from a regular contributor of yours truly’s blog. Yours truly would like to share the comment from IT.Scheiss with other readers. Than you IT.Scheiss for enlightening us on the subject matter.
Now let us examine this statement by Air Asia
“Indonesia AirAsia flight QZ7633 was taxiing in preparation for takeoff at the Surabaya airport – where last week’s doomed flight also took off – when a power unit used to start the plane shut down, an airline official said.”
An auxiliary power unit (APU) is a small jet engine usually mounted in the aircraft’s tail which powers the electrical generator to keep all electricity powered systems on the aircraft running, whilst the aircraft is on the ground with the main engines turned off. The APU also provides the electrical power for the starter of the main engines to get them running and generating electrical power themselves, after which the APU is no longer required, though sometimes the APU is left running to provide back-up power during the flight.
You can read more about APUs on Wikipedia.
Pratt & Whitney on APUs:
“Auxiliary Power Units (APUs) are gas turbine engines used primarily during aircraft ground operation to provide electricity, compressed air, and/or shaft power for main engine start, air conditioning, electric power and other aircraft systems. APUs can also provide backup electric power during in-flight operation. “. Please read HERE.
The You Tube video about a rather old APU on a Boeing 727 aircraft.
Notice the meticulous step by step procedures required when starting up and shutting down an APU
The more exciting video of the startup of an APU on a Boeing 747.
And on a Boeing 737
Here is a You Tube video of an APU failure on a Delta Airlines plane during push back from the parking bay but before the main engines were started.
Since the APU is a small gas turbine engine powered by the same jet fuel as the main engines, it is potentially dangerous if it catches fire or explodes and since it is usually mounted in the aircraft’s tail, an APU fire could spread and consume tioe rest of the aircraft’s fuselage where the passengers are.
So ask Tony what happened when the APU on that Air Asia flight failed with such a bang and why did it happen?
Why was it necessary for the APU to be kept running, whilst the main engines were running?