A320 Series - Radio Altimeter Reliability and Spurios ECAM Messages

[Flare-Idle]

Hello

During the past few winter months, a lot of our aircraft (EZY A320 series) have been affected by spurious ECAM Radio Altimeter failures (either NAV RA 1 FAULT or NAV RA 2 FAULT or both) in conjunction with following ECAMs:
ENG DUAL FAILURE
L/G SHOCK ABSORBER FAULT
ANTI ICE CAPT TAT
ANTI ICE F/O TAT

While those messages are attributed to operations on fluid contaminated runway/taxiway and referred to in FCOM 2, they have caused occasionally severe operational disruptions within our network.

Quote:
Airbus FCOM 2.4.10 Page 12: On contaminated runways and taxiways, the radio altitude indications may fluctuate and auto call outs or GPWS warnings may be activated. Disregard them.
During taxi on snowy runways, the radio altimeters may not compute any data and the ECAM warnings 'DUAL ENG FAILURE', 'ANTI ICE CAPT TAT FAULT', 'ANTI ICE F/O TAT FAULT', 'L/G SHOCK ABSORBER FAULT' may be triggered. Disregard these warnings.
Unquote.

All problems are encountered both in snowy as well heavy rain conditions. Obviously the reliability of our RA systems is not as expected and contributing factors seem to be the quality of the RA antenna seals and type IV anti-icing fluids.
I was wondering about similar occurrences/problems in other Airbus and/or BOEING/Embraer operator fleets ?
Thanks and Cheers

F.I.

[STBYRUD]

Never heard of anything similar on our 737-800s... All they do is fluctuate from -4 to -2 at most ;)

[K.Whyjelly]

We've received this advance FCOM/OEB notice from Airbus reference erroneous RA....................................



A318 MAR 10
A319
A320
A321 OEB PROC N° 201/2 6.00
PAGE 1 OF 2
RED OEB – RED OEB – RED OEB – RED OEB – RED OEB – RED OEB
Erroneous Radio Altimeter (RA) height indication
ECAM ENTRY: NONE
PROCEDURE:
This bulletin is issued to remind operators of the possible consequences of an erroneous Radio Altimeter (RA) height indication.
Erroneous RA height indication may have on aircraft systems, any of the effects listed in the OEB N°201 of FCOM Volume 3.
This OEB PROC N°201 is issued to provide flight crews with the following recommendations:
-
During all phases of flight, flight crew must monitor and crosscheck all primary flight parameters and the FMA.
-
During ILS (or MLS, GLS) approach with AP engaged, in the event of an unexpected early THR IDLE and FLARE modes engagement, the flight crew must immediately react as follows:
•
Immediately perform an automatic Go-Around (Thrust Levers set to TOGA),
OR
•
Immediately disconnect the AP,
–
Then continue the landing using raw data or visual references (FDs set to OFF),
OR
–
Perform a manual Go-Around (Thrust Levers set to TOGA). Significant longitudinal sidestick input may be required.
Note 1: If the flight crew does not immediately react, the angle-of-attack will increase and may reach the stall value.
Note 2: In case of Go-Around and if the RA is still frozen at a very low height indication:
-
SRS and GA TRK modes engage
-
NAV, HDG or TRK lateral modes cannot be selected
-
LVR CLB will not be displayed on the FMA at THR RED ALT
-
ALT* and ALT will not engage at FCU altitude
Disconnecting AP and resetting both FDs enable to recover basic modes (HDG and V/S).
Note 3: In CONF FULL, the auto-trim function is inhibited. Retracting one step enable to recover the auto-trim function.
-
For all the others events that may occur during approach, there is no change in the procedures or in the recommended flight crew reactions.
A318 MAR 10
A319
A320
A321 OEB PROC N° 201/2 6.00
PAGE 2 OF 2
Erroneous Radio Altimeter (RA) height indication (cont’d)
-
Flight crews must report in the aircraft technical logbook if any of the consequences on aircraft systems listed in the OEB N°201 of FCOM Volume 3, are seen.
END OF OEB PROC N°201/2

[Cardinal]

The Collins rad alt onboard the Beechcraft 1900 gets quite neurotic in slush and snow, it will regularly trigger a "500'" autocallout while taxiing.

On our Airbii I've noticed a few RAs written up this season, We don't carry FCOM2, I didn't realize there was a reference, thanks.

[nnc0]

To confirm faults are spurious, confirm RA on PFD is blank, then:

Dual ENG FAILURE - confirm engine parameters are normal.
ANTI ICE CAPT (F/O) TAT FAULT - can only be triggered in flight. Message is spurious when on ground.
LG SHOCK ABSORBER FAULT - Message is spurious as state of the shock absorber (extended/compressed) cannot change during the taxi phase.

Alternatively, taxiing to an uncontaminated surface should clear all of the faults once an RA can be computed.

[Dan Winterland]

I think that OEB is in response to the THY crash at AMS.

We haven't been getting those ECAM messages our fleet. But one thing I have noticed is that the RAD ALT aerials can get dity when the cabin crew tip coffee and wine down the forward sink. The spray from the forward drain mast leave a brown/purple residue on the underside and on the RAD ALT aerials. I've had RAD ALTs fail twice from this and I often ask the groundcrew to give them a clean after a walk around. Of course, if one had just failed because of being coated, the other may also be close and a double RAD ALT failure in the 'bus increases your workload somewhat!

Tends to happen more on 321s than 320s due to the longer fuselage.

[FlightDetent]

Flare-Ilde: Yes, a few times in past months (A32S). Some disruptions as well, memo issued to bring crews up to standard on FCOM2. How do you distinguish between a nuissance ECAM and genuine RA failure due to type II contamination, broken antenna seal etc? Not really answered.

nnc0: Cannot check ENG parametres once they're shut down and that is the only time you get ENG DUAL FAIL. I agree that probe and absorber warnings are not conclusive to failure of those systems but rather to RA issue. Clean taxiways not always available. :(

Sincerely,
FD (the un-real)

[Wizzaird]

Flare-Idle

We also get this problem very frequently on our fleet during winter months, especially in Eastern Europe with lots of recirculating snow during taxi. As long at it clears itself by the time you need to depart, no problem.