Reaching for wrong dial upsets Virgin 737, BNE>MEL [09/2023] • video based on ATSB report.

[Garfly]

 

 

A handy reminder to pay heed to the switches we flick till they're well and truly flicked.

 

 

 

[facthunter]

Something wrong with all that.   It's easy to see/check if the rudder trim is not centred.  I don't trust U tube to be authoritative. Nev

[onetrack]

We need to read the ATSB report, videos are noted for poor explanations and superfluous information.

 

https://www.atsb.gov.au/media/news-items/2024/inadvertent-rudder-trim-input-led-737-flight-upset

[facthunter]

There's an error in that also. It NEVER had FULL left trim. How to you centre rudder trim Quickly?    B 737 rubbish. Nev

[Garfly]

 

https://www.atsb.gov.au/sites/default/files/2024-11/AO-2023-042 Final.pdf

 

"In-flight upset involving Boeing 737-8FE, VH-YQR

143 km west of Ballina/Byron Gateway Airport, New South Wales

on 6 September 2023"

ATSB Transport Safety Report Aviation Occurrence Investigation

(Short) AO-2023-042 Final – 29 November 2024

 

EXCERPT:

 

"On the initial application of the rudder trim, both pilots felt the aircraft’s immediate yaw/roll response, but were unable to identify the likely cause. Over the following 5 seconds, while the captain maintained activation of the switch and waited for the door to open, the rudder trim progressively increased to the left, causing the rudder to correspondingly move to the left. The autopilot was initially able to compensate for the increasing left yaw input and induced left roll through application of increasing right wing down roll input. This right wing down input was replicated on the pilots’ control wheel.

After 5 seconds of trim input and increasing induced left roll, the autopilot reached its authority limit – that is, the autopilot had reached the maximum roll control input it could apply and maintain. Up to this point, the autopilot had managed to limit the induced roll to a bank angle of less than 5° to the left. However, on reaching the roll authority limit, the increasing rudder trim resulted in the aircraft’s bank angle to the left increasing. As the trim input continued for a further 3 seconds, the aircraft responded with a rapidly increasing rate of roll to the left.

The unexpected and increasing bank angle alerted both pilots to the developing aircraft upset. The PF initially responded by attempting to control the increasing left roll through the use of the mode control panel heading selections and the autopilot. As this had no apparent effect, and with the bank angle continuing to increase, the PF applied a large right wing down control input while almost simultaneously disengaged the autopilot and autothrottle. At about the same time the bank angle alert triggered. The PM responded with an ‘upset’ call, and the PF responded by executing the upset recovery procedure. The aircraft was quickly recovered to about straight and level flight.

Having recovered the aircraft to an approximate wings level attitude, the PF was required to hold about 35° of right wing down control wheel displacement to maintain that attitude. While this large roll input required to maintain a wings level attitude strongly indicated a yaw-related issue, the crew continued to investigate the cause of the inflight upset unsuccessfully for a further minute. About 70 seconds after the initial misapplication of rudder trim, the PF requested the PM check the rudder trim. Shortly after, the rudder trim was returned to a neutral position. While large right wing down aileron input required to maintain a wings level attitude provided a strong indicator that the upset was linked to a yaw related issue, a combination of the very small displacement of the rudder pedals at the point of maximum trim application, and the PF’s limited experience on the aircraft, probably contributed to some of the delay in identifying the unintended rudder trim."

 

 

Edited February 5 by Garfly

[Blueadventures]

5 hours ago, facthunter said:

Something wrong with all that.   It's easy to see/check if the rudder trim is not centred.  I don't trust U tube to be authoritative. Nev

Maybe not, the switch was held on because, maybe the door switch needs to held on so the electrical circuit closed to allow entry as when let go it goes open circuit (perhaps so cannot be inadvertently left in the unlocked mode.   I not a commercial pilot so just a guess. 

[facthunter]

Stupid to have such similar switches near each other. Manual trim is instant almost and bigger planes that the 737 have it. It should also have a  "Trim actuating" warning light. otherwise it's an accident waiting to happen. Nev