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FLIGHT OPERATIONS TRANSMISSION - FOT
TO: All A319-100N, A320-200N, A321-200N, A321-200NX Operators
SUBJECT: ATA 00 – OEB 59 REINFORCE SPEED CHECK FOR ROTATION MODE OUR REF.: 999.0042/21 Rev 00 dated 21-JUN-2021
CLASSIFICATION: Airworthiness or Safety
APPLICABLE AIRCRAFT: This FOT is applicable to all A319neo/A320neo/A321neo Airbus aircraft.
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.
REFERENCES
1. FOT 999.0041/21 ATA 00 – WEBINAR - OEB 59 REINFORCED SPEED CHECK DURING
TAKEOFF of June 3, 2021. 1. PURPOSE
The purpose of this FOT is to inform all A319neo/A320neo/A321neo Operators that the Red OEB number 59 Reinforced Speed Check for Rotation Mode has been published. OEB 59 and the associated webinars were announced via FOT [REF 1].
2. DESCRIPTION
Between January 2020 and March 2021, several events of unreliable airspeed indication during takeoff were reported to Airbus. Most of the reported cases were due to pitot obstruction by insect contamination. In one of the reported cases, probe cover removal was not completed before flight.
Based on those in-service experiences, Airbus decided to analyze and understand this specific increase of unreliable airspeed indication events and published several recommendations.
Airbus has performed an additional study, and has identified the following: in the case of an unreliable airspeed situation, defined by an erroneous and consistent airspeed on at least two ADRs, the Rotation Mode computation may be degraded. This degradation may result in an unstable flight path after rotation on A319neo, A320neo and A321neo aircraft.
3. CAUSES / CONSEQUENCES
3.1 Cause
The aircraft airspeed is an essential parameter for the flight controls computation during takeoff, particularly when the Rotation Mode is operating.
FOT ref: 999.0042/21 Rev 00 Page 1 of 3 Date: 21-JUN-2021 © AIRBUS S.A.S. 2021. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT
FLIGHT OPERATIONS TRANSMISSION - FOT
The Rotation Mode is an ELAC function that has been included in the most recent Airbus aircraft types, and particularly on the A320neo family. This function provides an homogeneous rotation for all possible weights, CGs and configurations, while it minimizes a possible tail strike. The Rotation Mode is a flight control law that makes a sidestick input become a pitch rate demand. The principle of the law is based on the fact that the elevator deflection is dependent on the airspeed:
At low airspeed, it corresponds to a large elevator deflection
At high airspeed, it corresponds to a low elevator deflection.
This design enhances the rotation phase and requires a reliable airspeed. If the airspeed considered by the Rotation Mode is erroneous, the elevator deflection may not be appropriate for a correct rotation.
The Rotation Mode computation relies on the airspeed monitoring function. By design, the airspeed monitoring function keeps airspeeds, when they are below a certain threshold of difference one from the other. Therefore, the airspeed monitoring function may:
Keep the two airspeeds, because they are below the threshold
Reject the remaining airspeed, because it is above the threshold.
In the case of an unreliable and consistent airspeed on two ADRs, the following may occur:
The correct airspeed is rejected, because it is above the threshold
The two erroneous airspeeds are kept, because they are below the threshold.
Then, the airspeed considered by the Rotation Mode is erroneous and the Rotation Mode may be degraded.
3.2 Consequences
The Rotation Mode may be degraded and may result in an unstable flight path after rotation with the combination of all of the following conditions:
A double erroneous ADR airspeed indication
Both affected ADRs provide a similar erroneous airspeed indication
The erroneous airspeed is underestimated by at least approximately 30% of the real aircraft
airspeed
The takeoff is continued.
From an operational point of view, the “approximately 30 %” of error is difficult to monitor during the takeoff roll. Therefore, this “approximately 30 %” parameter has been translated into a fixed operational parameter. The value of 20 kt airspeed error is kept based on:
Simulation studies
Margins: instrument uncertainties and crosswind effect on airspeed indications.
4. AIRBUS ACTIONS
Although there were no in-service case reports, Airbus decided to mitigate the possible degradation of the Rotation Mode via the Red OEB 59 Reinforced Speed Check for Rotation Mode, applicable to A319neo, A320neo and A321neo aircraft.
OEB 59 aims to ensure that, during the takeoff roll, the two PFD airspeed indications are not consistent in an erroneous way. In order to achieve that, the airspeed check during the takeoff roll before V1 is reinforced as follows:
The two PFD airspeed indications must be crosschecked with the ISIS airspeed indication
A value of 20 kt of airspeed error is to be considered
An additional airspeed crosscheck is added at 80 kt
The current SOP 100 kt crosscheck is reinforced.
FOT ref: 999.0042/21 Rev 00 Page 2 of 3 Date: 21-JUN-2021 © AIRBUS S.A.S. 2021. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT
FLIGHT OPERATIONS TRANSMISSION - FOT
In addition, OEB 59 requires the ISIS airspeed indication. Therefore, ISIS becomes a “must be operative item”. The MMEL was updated accordingly.
5. FOLLOW-UP PLAN
OEB 59 and MMEL update will be released to Operators with an unplanned major event revision. An advanced copy of the operational documents are attached to this transmission.
In addition, the associated AFM Temporary Revision TR 787 is approved by the authorities. The AFM TR 787 will be released in the June 2021 AFM revision.
OEB 59, the associated AFM TR and MMEL impact will be cancelled by ELAC L103+ planned fourth quarter 2021.
For any questions about the operational content of this FOT, please use TechRequest on AirbusWorld.
Best regards,
Capt. Yann LARDET
Vice President, Flight Operations Support & Training Standards
FOT ref: 999.0042/21 Rev 00 Page 3 of 3 Date: 21-JUN-2021 © AIRBUS S.A.S. 2021. ALL RIGHTS RESERVED. CONFIDENTIAL AND PROPRIETARY DOCUMENT
OPERATIONS ENGINEERING BULLETINS
RED OEB – RED OEB – RED OEB – RED OEB – RED OEB – RED OEB – RED OEB
A318/A319/A320/A321
18 JUN 21
59.01A
QUICK REFERENCE HANDBOOK
REINFORCED SPEED CHECK FOR ROTATION MODE - PROCEDURE
ECAM ENTRY
None
PROCEDURE
Apply this procedure at each takeoff:
AT ANY TIME during the takeoff roll before V1, in the case of an
unreliable airspeed indication: ABORT TAKEOFF At 80 kt:
PFD/ISIS SPEEDS...................................................... .............CROSSCHECK
The PM must silently reinforce the IAS scanning by crosschecking own PFD speed and ISIS speed.
In the case of an airspeed difference of more than approximately 20 kt: ABORT TAKEOFF
At 100 kt:
PFD1/PFD2 SPEEDS...................................................... ........ CROSSCHECK
Apply this check as per the Standard Operating Procedures/100 kt crosscheck.
In the case of an airspeed difference of more than approximately 20 kt: ABORT TAKEOFF
OEB59 Issue 1
OPERATIONS ENGINEERING BULLETINS
RED OEB – RED OEB – RED OEB – RED OEB – RED OEB – RED OEB – RED OEB
ROOT CAUSE
The aircraft speed is an essential parameter for the computation of flight controls during takeoff. In the case of an unreliable and consistent airspeed on 2 ADRs, the Rotation Mode computation may be degraded.
OPERATIONAL CONSEQUENCE
The Rotation Mode degradation may result in an unstable flight path after rotation.
END OF OEB59
A318/A319/A320/A321
18 JUN 21
59.02A
QUICK REFERENCE HANDBOOK
REINFORCED SPEED CHECK FOR ROTATION MODE - EXPLANATION
OEB59 Issue 1
A319/A320/A321
TEMPORARY REVISION TR787 issue 1
TR 787 - A320NEO FAMILY REINFORCED SPEED CHECK FOR ROTATION MODE
AIRPLANE FLIGHT MANUAL
The content of this document is the property of Airbus. It is supplied in confidence and commercial security on its contents must be maintained. It must not be used for any purpose other than that for which it is supplied, nor may information contained in it be disclosed to unauthorized persons. It must not be reproduced in whole or in part without permission in writing from the owners of the copyright. © AIRBUS 2005. All rights reserved.
REFERENCE: TR787 Issue 1 AFM ISSUE DATE: 17 JUN 21
PRELIMINARY PAGES
A319/A320/A321
AIRPLANE FLIGHT MANUAL
PRELIMINARY PAGES TABLE OF CONTENTS
APPRO APPROVAL DATA
APPRO-TR TEMPORARY REVISIONS
Reinforced Speed Check for Rotation Mode........................................................ .................................................. A
NORM NORMAL PROCEDURES
NORM-TO TAKEOFF
Takeoff Procedure................................................... ............................................................ .................................... A
TR787 Issue 1 PLP-TOC P 1/2 AFM 17 JUN 21
A319/A320/A321
AIRPLANE FLIGHT MANUAL
APPROVAL DATA TEMPORARY REVISIONS
TR787 Issue 1
REINFORCED SPEED CHECK FOR ROTATION MODE
Ident.: TDU / APPRO-TR-00024785.0001001 / 17 JUN 21 EASA APPROVED Criteria: (319-100N or 320-200N or 321-200N or 321-200NX)
Impacted DU: NONE
APPROVAL REFERENCE
Do not remove this Temporary Revision until instructed to do so.
Reason for issue: This Temporary Revision (TR) is issued in order to reinforce the speed check during take-off.
Applicable to: All A319neo, A320neo, and A321neo.
This Temporary Revision is made up of the following Temporary Documentary Units:
APPRO-TR-00024785.0001001/17 JUN 21 NORM-TO-00024786.0001001/17 JUN 21
APPROVED BY: EASA
Approval date: 17 JUN 21 Approval reference: 10076715
TR787 Issue 1 APPRO-TR P 1/2 AFM A 17 JUN 21
A319/A320/A321
AIRPLANE FLIGHT MANUAL
NORMAL PROCEDURES TAKEOFF
TAKEOFF PROCEDURE
Ident.: TDU / NORM-TO-00024786.0001001 / 17 JUN 21 EASA APPROVED Criteria: (319-100N or 320-200N or 321-200N or 321-200NX)
Impacted DU: NONE
Belongs to TR787 Issue 1
In addition to the normal Takeoff Procedure, apply the following reinforced speed crosscheck at each takeoff.
Anytime during the takeoff roll before V1, the takeoff must be aborted in the case of:
‐ An unreliable airspeed situation, or
‐ An airspeed difference of around 20 kt (and above) between any of the ASI (PF ASI, PM ASI and
ISIS ASI).
TR787 Issue 1 NORM-TO P 1/2 AFM A 17 JUN 21