A320 fuel temp limitation

[Tiennetti]

Hello guys,
LIM-28 FUEL establishes the meximum temperature for JET A1 at 54º

You will have the advisory for the inner cells at 45º and for the outer at 55, with the only instruction to switch off Galley Power
Being an advisory, i would be inclined to takeoff, knowing that soon the temperature will drop, but... am I busting the fuel limitation?

Curiously enough, FUEL INNER(OUTER) HI TEMP ECAM will be triggered when inner temp is 54, or outer 60, this time tellig you to delay takeoff

What I am wondering now is, what kind of fuel limitation is that?
FCOM doesn't specify if it is a general limitation or if the fuel cannot be used over that temp (takeoff will be done on inner tank feeding)

Anyone able to shed some light on this? Thanks!

[DutchOne]

Curiously enough, FUEL INNER(OUTER) HI TEMP ECAM will be triggered when inner temp is 54, or outer 60, this time tellig you to delay takeoff

Don't know what the fuel feed sequence is on the 320, but I think fuel will go from outer tk to inner tk to engine, is that right?

If so the 60 degrees is the limit because as long as it is in the outer tk it will not go to the engine anyways. It has enough time to cool down below the 54 degrees before it transfers to the inner tank.

From my FCOM Hot fuel in the engine can lead to engine stall, engine shutdown, or engine overspeed. So for ops reasons it can be allowed to have an higher temp in the smaller (easier to heat up) outer tank, as it doesn't feed the engine.

What you think.

[Tiennetti]

DutchOne, you are right, fuel is used from inner during takeoff, central (if any) are emptied in flight, the outer fuel is spilled onto inner.
Hot fuel returning from the engine is sent to the outer and excess spilled to the inner (that is the reason while it is normally warmer than the inner)

I had exactly the same tought, that 54º is a limitation to USE the fuel, but the vague FCOM wording made me doubt

Thanks for your answer

[FlightDetent]

Hi, I like your reasoning and think it is makes a lot of sense.

If I was to play devil's advocate, these would be the observations:

The relevant guiding documents here are OM-B*, and AFM. We are expected to operate within the prescrbed limits, even when FCOM, ECAM or else do not warn us (yet).
AFM clearly states FUEL TEMPERATURE LIMIT maximum +54 deg C. If the fuel temperature indication is correct** and above this limit, the aircraft is beyond certified state.

cheers,
FD.

* FCOM is a legal part of OM-B here, a common setup I suppose;

** I had experienced HI TEMP indication while no. 1 at holding point of a very busy international airport. With all the bells and whistles you describe Tiennetti, including a very straightforward ECAM action line to shut down the engine. Here's what I found in FCOM later on, hidden to me until later that day:

This caution may spuriously trigger due to interference from communication equipment. Therefore, the flight crew should wait 2 min while the fuel temperature measurement is updated. After 2 min, if the ECAM caution has not disappeared, the flight crew must apply the following procedure:

[Metro man]

I've had this caution a couple of times in flight when using HF radio. Very rapid temperature rise indicated, then it returned to normal.

[nnc0]

Curious note to add re cold temps

Unlike the A330 in which you can specify fuel type, the A320 limit cold temp limits are based on Jet A1. A lot of our destinations use Jet A which isn't as resistant to cold temps and has a higher cold temp limit. If your flying with Jet A then there is no ECAM warning to advise you until after the limit.