A320 Questions
 

Hi folks,

im having some specific 319/320/321 questions. Would appreciate some good explanations:

1. Why did airbus install the feature on the 320 that with AP engaged the speedbrake comes out only half way? is that also with flaps out the case( AP on) ?

2. Why do we have to reset the center tank pumps after fueling for 10 seconds? Why does the aircraft not do it on its own?

3.Is it true that the brake fans cool the brakes for a possible spill of hydraulic fluid in the gear bay when the gear is retracted so that the risk of a fire is not there?

4.Why does the airbus manual say at landing take max reverse? is it something with procedures in a catIII approach? I think idle reverse is sufficient . But why do we have to pull them full back?

5. Does somebody have a good mean value for N1 on a A321 on final? Don´t like this EPR indications. Any tips or tricks?

6. When we get the nav accuracy downgrade message and the FMS show Low. So we are flying inbound a fictional Waypoint RNAV, whats the best solution? Request a heading?


Thanks folks!

Hi Speedwinner,

1) Originally the autopilot could not cope very well with full speedbrake.
See ------ OAVIAO.COM ------> The A319 autopilot is now able to cope with the pitch rate change, but apparently it has still not been solved for A320.

2) During refuelling with the centre tank fuel pumps selected on and auto, a software glitch allows the pumps to run. With no fuel in the tank, the pumps can become unprimed which has led to having about 200 kgs of unusable centre tank fuel. Problem can only be resolved by re- priming the pumps by putting about 500 kgs into the centre tank.

3) The brake cooling fans allow quick turn arounds and be ready for take off with the brakes below 300C (limitations).

4) Airbus state the procedure for minimum stopping distance on wet runways. Depending on runway length, braking action etc. you may be able to use idle reverse. (Our SOP)

5) I prefer EPR. If I needed 1.2 EPR on the approach with 2 engines, the I'd need 1.4 EPR with only 1 engine. EPR is very intuitive.

6) If NAV position accuracy (on the progress page) is outside limits, then you have to request a re-clearance (radar heading or use VOR etc).

Hmm - if it were truly a "glitch", I suspect it would have been fixed by now given the amount of time the series has been in service. My guess is that it's more likely to be a deliberate behaviour pattern that seems quirky in a ground-based refuelling scenario.

Hi DozyWannabe,
Originally, AirBus procedures were to turn all fuel pumps off during the "after shut down checks". When we initially operated them, with 30 minute turn rounds, one of the first items was turn them back on again (all white lights extinguished). We obtained a no technical objection from AirBus to leave the pumps turned on during turn arounds. We then had a spate of the centre tank pumps running for 5 minutes (timer logic) when the refuelling panel was opened. Software glitch?

Since we hardly ever carry centre tank fuel on our short sectors, the pumps would eventually run so dry that we would loose pump priming fuel and the pump pressure low caution "ding" on every turnaround, and subsequently found some aircraft had up to about 200 kgs of unusable fuel in the centre tank.

Speedwinner
The reason to reset center tank pumps and removal of this requirement is given below.

MODIFICATION NUMBER
30961
(SB 28-1092)


This modification deletes the requirement to reset the MODE SEL pb on the overhead fuel panel when refueling from the cockpit refuel panel
A logic is introduced to latch off the center tank pump once the center tank is empty in flight. The pumps were normally unlatched during the next refueling by opening the refuel panel door. This was not the case, if the pilot chooses to command the refueling from the cockpit, and the center tank pumps remained latched off.
As a consequence, the AUTOFEED FAULT was generated on the next flight leg.
To avoid this behavior, a reset of the MOD SEL pb on the cockpit overhead panel has been introduced into the FCOM refueling procedure 2.01.30.

Also it is not mandatory to select MAX reverse depending on LDA you may select reverse idle only.