Airbus A330/A340 OEB (Operational Engineering Bulletin)

[Don Hudson]

FROM : AIRBUS CUSTOMER SERVICES TOULOUSE

TO : ALL A330/A340 CFM GE PW RR OPERATORS

FLIGHT OPERATIONS TELEX - FLIGHT OPERATIONS TELEX

OUR REF. : 999.0112/10 dated 20 December 2010

Subject: ATA 22 and 34 - Loss of AP and A/THR associated with alternate law reversion

CLASSIFICATION: AIRWORTHINESS

Notice: This FOT provides information about a significant operational issue that is related to airworthiness or safety. It is each Operator´s responsibility to distribute this FOT or to distribute the information contained in this FOT, to all of their applicable flight crews without delay. Failure to apply this FOT may have a significant impact on safe aircraft operations. This FOT and the OEB advance copies will be available in pdf format in AirbusWorld within two days.

1. PURPOSE

The purpose of this FOT is to recommend the flight crew to check airspeed indications before engaging the autopilot, when in alternate law.

2. EXPLANATION

When there are significant differences between all airspeed sources, the flight controls revert to alternate law, the autopilot (AP) and the autothrust (A/THR) automatically disconnect, and the Flight Directors (FD) bars are automatically removed. It has been identified that, after such an event, if two airspeed sources become similar while still erroneous, the flight guidance computers:

•Display FD bars again.

•Enable autopilot and autothrust re-engagement.

However, in some cases, the autopilot orders may be inappropriate, such as possible abrupt pitch command. Therefore, the flight crew must apply the following procedure.

3. OPERATIONAL RECOMMENDATIONS

When autopilot and autothrust are automatically disconnected and flight controls have reverted to alternate law:

•Do not engage the AP and the A/THR, even if FD bars have reappeared

•Do not follow the FD orders

•ALL SPEED INDICATIONS......................................X-CHECK

If unreliable speed indication is suspected:

UNRELIABLE SPEED INDIC/ADR CHECK PROC...........APPLY

If at least two ADRs provide reliable speed indication for at least 30 seconds, and the aircraft is stabilised on the intended path:

AP/FD and A/THR ......................................As required.

4. CORRECTIVE ACTION

This procedure will be cancelled by the next FCPC standards that will be available before end 2011. This modification will inhibit autopilot engagement in the above described situation.

5. FOLLOW-UP

For A330 aircraft, these operational recommendations will be issued by beginning of January 2011 in red OEB 82/1 and its associated OEB PROC 82/1 in the QRH. For A340-200/-300 aircraft, these operational recommendations will be issued beginning of January 2011 in red OEB 95/1 and its associated OEB PROC 95/1 in the QRH.

No specific follow-up to this FOT is planned.

[Specs]

Kind of funny when juxtaposed to the all operators all fleets message issued around the same time

1. REASON FOR ISSUE

EASA has recently issued the SIB (ref1) to address the general Flight Deck Automation policy with the objective to recommend operators to develop an automation policy in cooperation with airplane manufacturers.

The purpose of this FOT is to remind the existing Airbus operational documentation that can be used by the operators to develop or update an Automation Policy, as recommended by the EASA SIB.

2. AIRBUS OPERATIONAL DOCUMENTATION

- Airbus Flight Operations Briefing Notes (FOBN) Optimum Use of Automation, issued on January 2004

- Flight Crew Training Manual:

. A320/A330/A340/A380 - FCTM/Operational Philosophy

. A300-600/A310 - FCOM/FCTM -2.31/Operational Philosophy

- A300FFCC - FCOM 2.02.05/AFS/Use of AFS

- A300B - FCOM 8.03.05 (GE)/8.02.06 (PW) - Use of AFS

3. SUMMARY OF KEY POINTS FROM THE ABOVE MENTIONED AIRBUS FOBN

For optimum use of automation, the following should be promoted:

- Understanding the integration of AP/FD and A/THR modes (i.e., pairing of modes);

- Understanding all mode transition and reversion sequences;

- Understanding pilot-system interfaces for:

. Pilot-to-system communication (i.e., for modes engagement and target selections);

. System-to-pilot feedback (i.e., for modes and targets cross- check);

- Awareness of available guidance (AP/FD and A/THR status, modes armed or engaged, active targets);

- Alertness to adapt the level of automation to the task and/or circumstances, or to revert to hand flying / manual thrust control, if required;

- Adherence to design philosophy and operating philosophy, SOPs and Operations Golden Rules.

[Mitch Cronin]

Interesting... I don't see them as juxtaposed at all... I see them as complimentary... Combined, they seem to be saying: Get to know your aircraft.

[Don Hudson]

Combined, they seem to be saying: Get to know your aircraft.

Precisely.

Also, I don't see this OEB as a high possibility in the AF447 accident. I say this because, while the order of the ACARS messages may not be the actual order of failures, I expect that the messages towards the end of the ACARS series still would have prevented the autoflight/autothrust systems from being re-engaged. And if that were a possibility, the pitch response would likely be down because the speed was almost certainly on the very low side of normal as all other such A330 events indicated. If the speed "defaulted" to the high side, one could see a pitch-up, (beyond the control of the pilots), with commensurate loss of airspeed and resulting stall but that is purely conjecture as there is such scant evidence of anything.