ocirocir
  • Member for 6 years, 1 month
  • Last seen this week
  • Europe
Have attitude indicators ever had triple failure in a commercial aircraft?
Accepted answer
11 votes

Yes! More or less, it depends on your definition of failure (see later). As you said, the probability that three Inertial Reference Units (IRUs) fail is extremely rare. This is because IRUs are self-...

View answer
Why do landing gear bays in commercial aircraft not have a fire extinguishing system?
Accepted answer
8 votes

Cost/Weight/Complexity, the usual reasons why you avoid to add another systems. But let's analyse if you really need it. Easy to prevent From the data of this Boeing document: at least 62% of the ...

View answer
Where is the fire suppression material injected into a jet engine?
Accepted answer
6 votes

I’m wondering where exactly does the suppression material go into the engine? Does it all flow into the core or is it distributed to different places. It is distributed with some nozzles. But the ...

View answer
Why are some item numbers missing in ICAO flight plans?
5 votes

From the FAA page: Item numbers on the form are not consecutive, as they correspond to Field Type numbers in ATS messages Here you can find a description of ATS messages.

View answer
Why the excessive wait after shutdown before using the manual starter valve on the PW1000G?
5 votes

The FCOM page reports MSN 7172 which corresponds to an A320neo with PW1127G engines. Why is this important? Because this engine family is prone to bowing, so much that it requires a dedicated cooling ...

View answer
Why was blue hydraulic system chosen for RAT?
5 votes

Because in A320 is the only hydraulic system independent from the engines and isolated from the other two hydraulic systems (while G and Y have the PTU in common). Also the B hydraulic system is able ...

View answer
Why does the A320 IR2 MEL OPS procedure suggest to switch to ADR3?
4 votes

Even if ADR and IR perform two independent and separate functions, they are the same hardware object (example). A IR2 malfunction is a malfunction: you do not know, in general, what is causing the ...

View answer
How often is the cabin air replaced in A320?
4 votes

Let's do some simplified arithmetic: The packs airflow in an A320 is 1.2 kg/s per pack in HIGH setting, but let's take the normal setting 1 kg/s, thus 2 kg/s considering both packs The cabin of an ...

View answer
What is the rationale behind placing arrestor gear on a long runway?
Accepted answer
3 votes

I can think of 4 reasons: Pilot Training to use the cable arresting system Rejected takeoff, fighters don't usually have reversers and may take long space to arrest Under certain bad runway ...

View answer
How does the A320 FMGC (autothrust, autopilot) decide which radio altimeter readings to use?
3 votes

First of all, RA1 is showed on the captain PFD and RA2 is showed on the F/O PFD. If one is detected as failed, the functional one is showed in both PFDs. This behavior is fixed, there is no way for ...

View answer
Why is this equation for TAS only valid for subsonic flow?
Accepted answer
2 votes

Because you didn't read the text in the Wikipedia page above that equation ;-) That equation works for subsonic flow only because you have replaced the Mach number of the original TAS formula: $$ \...

View answer
How many LRUs are there in modern aircraft like a Boeing 747 or an Airbus A380?
2 votes

It's difficult to precisely answer your question, because they are not public information and depend on the aircraft sub-model, customer configuration, etc. I built this approximate plot using the ...

View answer
What is in the A320 Smoke and Fume checklist?
2 votes

I'm resuming this old question because no answer was given. It depends on where the smoke is detected (if automatically detected). The following abnormal procedures exist: SMOKE FWD(AFT) CARGO SMOKE ...

View answer
If the APU is switched off but the APU bleed is on, will the engine bleed valve close automatically?
2 votes

The answer is in the FCOM: So, the ENG bleed valve closes if: Reverse flow detected ENG 1 starter valve not closed APU bleed valve open Bad things (Overpressure / Overheat / Leak) ENG BLEED switch ...

View answer
What kind of heaters are used for heated floor panels?
1 votes

Electrical, connected to one of the AC buses. This is an example, absorbing 620 watts/m^2.

View answer
What RA will be generated if intruder traffic is at our level in TCAS II?
0 votes

It is not possible to give an answer, because the TCAS II RA algorithm is not so simple. It isn't like "if A is 50 feet above B then A climb and B descent", it consider many different ...

View answer