FBW A320NEO starts banking heavily to the right initiating a dive a minute after fuel starvation

[xMaxNGX]

Aircraft Version

Development

Build info

{
    "built": "2024-01-11T06:47:54+00:00",
    "ref": "refs/heads/master",
    "sha": "86560d7306a1109e1d99d4e68480b7c18962640e",
    "actor": "Saschl",
    "event_name": "manual",
    "pretty_release_name": "master:86560d73",
    "version": "v0.12.0-dev.86560d7"
}

Describe the bug

After one minute of fuel starvation and with no controls connected and rudder trim set to 0 as well as resetting it right before said fuel starvation - plane starts banking to the right initiating a dive. It seems to me the plane should fly straight and be gliding, and not start causing a bank/dive a long way before reaching stall speed.

Expected behavior

The plane should continue flying straight in a nose down position.

Steps to reproduce

1. Start the aircraft and fly it to any altitude
2. Stabilize the aircraft at said altitude
3. In the EFB, set fuel to 0 while making sure rudder trim is set to 0
4. Engines should be shutting down. Wait a minute, the plane should start banking and diving.

References (optional)

https://cdn.discordapp.com/attachments/216673611753193473/1195069931377659934/FlightSimulator_nwxTz2ElYm.mp4?ex=65b2a69a&is=65a0319a&hm=2fe5512f04ecc264bc54903f35cd72c80daa04b64aef7aef4d859c0138071d71&

https://cdn.discordapp.com/attachments/216673611753193473/1195071823151382629/FlightSimulator_aix8KZFZKU.mp4?ex=65b2a85e&is=65a0335e&hm=5a77e86030926678c7b9a1171d64b67557cd78faf284d57b75f0f913723a3d14&

Additional info (optional)

No response

Discord Username (optional)

No response

[xMaxNGX]

Another video https://cdn.discordapp.com/attachments/283145023372132372/1195075305761673216/FlightSimulator_p5TdlYPme9.mp4?ex=65b2ab9c&is=65a0369c&hm=fdc6ec1b7029dd5ace8bd8d324314cc61363976da4ee077478fac1304a7ec92d&

[xMaxNGX]

The banking starts as "HYD PTU" is displaying for a split second on the ECAM and I have a suspicion it might be related to that. Full reproduction video without weather: https://cdn.discordapp.com/attachments/1023288811045781514/1195080077101256836/FlightSimulator_rBnPRDK9NQ.mp4?ex=65b2b00d&is=65a03b0d&hm=3289cbcc152625a98dec09b7cc82a0159795e093d824e00a5a972b752d5dd911&

[xMaxNGX]

[xMaxNGX]

When the APU is turned on or any other source of electrical power, this banking towards the right stops

[Popespice]

Working as designed. When you lose the engines and APU you lose all hydraulic/electric control systems. The RAT helps with some of the electric systems but that's only a couple of flight control surfaces.

OK to close issue.

[xMaxNGX]

Hey @Popespice,

Issue being: After 1 minute of the aircraft engines being shut down, HYD PTU displays on ECAM for one second, disappears and then the aileron gets stuck in full right position and stays there unless APU is turned on or any other source of electrical power.

[xMaxNGX]

Aileron inputs: https://cdn.discordapp.com/attachments/216673611753193473/1195099680275701770/FlightSimulator_citGCpC4Se.mp4?ex=65b2c24f&is=65a04d4f&hm=5269456b9dd1000c286badae13519bdc68be19751b047ff2066c4d3f2e153532&

Left is freely moving, right is stuck

[jbud]

Working as designed. When you lose the engines and APU you lose all hydraulic/electric control systems. The RAT helps with some of the electric systems but that's only a couple of flight control surfaces.

OK to close issue.

The RAT pumps the BLUE hydraulic system and the blue system powers the emergency generator. The BLUE system is also connected to ailerons elevator and slats as well as elevator 3

[tshomas]

Evening everyone,

The team are currently discussing this, there's a possibility that the ELAC 2 had an incorrect logic state concerning the blue hydraulics, which was causing the aileron to default into its zero hinge position (in this case slightly up) which then caused the roll rate.

There is more examining ongoing of some deep level system diagrams, stand by for more info as it comes!

Cheers for the reporting