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Accident
Last updated: 17 October 2017
Status:Offizieller Zwischenbericht
Datum:Donnerstag 20 Februar 2014
Zeit:16:40
Flugzeugtyp:Silhouette image of generic AT76 model; specific model in this crash may look slightly different
ATR 72-212A (ATR-72-600)
Fluggesellschaft:Virgin Australia Regional
Kennzeichen: VH-FVR
Werknummer: 1058
Baujahr: 2012-11-12 (1 year 3 months)
Triebwerk: 2 Pratt & Whitney Canada PW127M
Besatzung:Todesopfer: 0 / Insassen:
Fluggäste:Todesopfer: 0 / Insassen:
Gesamt:Todesopfer: 0 / Insassen:
Sachschaden: schwer beschädigt
Konsequenzen: Repaired
Unfallort:47 km (29.4 Meilen) WSW of Sydney, NSW (   Australien)
Flugphase: Während des Fluges (ENR)
Betriebsart:Inländischer planmäßiger Passagierflug
Flug von:Canberra Airport, ACT (CBR/YSCB), Australien
Flug nach:Sydney-Kingsford Smith International Airport, NSW (SYD/YSSY), Australien
Unfallbericht:
An ATR 72-600 sustained damage in a in-flight pitch disconnect event near Sydney Australia.
The flight departed Canberra, Australia at 16:12 local time with the first officer as the pilot flying. A steeper-than-usual climb was carried out to reduce exposure to turbulence. However, other than the expected turbulence during the first 1,500 ft, there was nothing significant during the climb to FL170.
During cruise, the crew conducted a routine brief for the anticipated arrival to runway 16R, which was expected to be standard except for commencement of descent 5 NM (9 km) earlier than normal to compensate for a tailwind. The captain noted the need to be cognizant of managing airspeed during the descent as the anticipated decreasing tailwind would result in a temporary increase in the indicated airspeed.
The first officer commenced descent into Sydney with the autopilot engaged in vertical speed mode and a target airspeed of 235 kt (15 kt less than the maximum operating speed of 250 kt). The descent was reported to have been initially stable and smooth.
On first contact with Sydney Approach the crew were assigned runway 16L. This was different to the expected runway and required the crew to re-brief the approach and change the instrument approach diagrams and navigational aid frequencies.
Passing 8,500 ft above mean sea level (AMSL), the crew noticed a rapid airspeed increase. The first officer reported that the airspeed trend indicator was 'off the chart', indicating a very rapid increase in airspeed. The first officer reduced engine power and used touch control steering to temporarily disconnect the autopilot before manually raising the aircraft's nose to control the speed. The first officer expected that, in combination, the pitch correction and power reduction would be sufficient to arrest the speed trend.
The first officer reported that the aircraft felt 'heavy', as was normal for this aircraft at that speed, requiring two hands on the controls to move from the then -4° pitch angle.
The captain reported being unsure if the first officer's control inputs would be sufficient to avoid exceeding the maximum operating speed limitation, so put one of his hands on the controls and disconnected the autopilot to raise the nose further.
Shortly after, with both flight crew making simultaneous nose up pitch inputs on the controls, the aircraft rapidly pitched up with an associated increase in the g load. The first officer responded by immediately reversing the control input to nose down. Both flight crew noticed that the controls suddenly felt different and 'spongy'. At about the same time, aural and visual cockpit warnings activated. The crew verified that the aircraft was under control at a stable attitude and speed, observing that it was level or in a slight descent at an airspeed of about 230 kt.
One of the cockpit warnings was 'pitch disconnect', indicating that the left and right elevator control systems had uncoupled from each other. This allowed for independent movement of the left and right elevators via the captain's and first officer's control columns respectively.
The crew consulted the pitch disconnect checklist and worked to identify which control column was free and working normally. After determining that both controls were free, it was decided that the captain would be pilot flying for the remainder of the approach and landing at Sydney Airport. The aerodynamic loads generated during the pitch disconnect resulted in serious injury to the senior cabin crew member and significant damage to the aircraft's horizontal stabiliser. Although the aircraft was inspected after the pitch disconnect, the damage was not identified until 25 February 2014.

On 15 June 2016 the ATSB released an interim investigation report that contained the following safety issue:
- Inadvertent application of opposing pitch control inputs by flight crew can activate the pitch uncoupling mechanism which, in certain high-energy situations, can result in catastrophic damage to the aircraft structure before crews are able to react.

While this issue focused on the potential for catastrophic damage during inadvertent activation of the pitch uncoupling mechanism (PUM) from opposing dual control inputs, additional investigation identified that the inherent behaviour of the elevator control system design could potentially result in an ultimate load exceedance from the deliberate activation of the PUM to overcome a jam. Based on the results of this additional investigation, the ATSB made the following finding on May 5, 2017:
- The aircraft manufacturer did not account for the transient elevator deflections that occur as a result of the system flexibility and control column input during a pitch disconnect event at all speeds within the flight envelope. As such, there is no assurance that the aircraft has sufficient strength to withstand the loads resulting from a pitch disconnect.

Accident investigation:
cover
Investigating agency: ATSB
Status: Investigation ongoing
Duration: 3 years and 3 months
Accident number: AO-2014-032
Download report: Preliminary report


Fotos

photo of ATR 72-600 (72-212A) VH-FVR
photo of ATR 72-600 (72-212A) VH-FVR
photo of ATR 72-600 (72-212A) VH-FVR
FDR graph
photo of ATR 72-600 (72-212A) VH-FVR
FDR graph
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Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Canberra Airport, ACT to Sydney-Kingsford Smith International Airport, NSW as the crow flies is 236 km (147 miles).

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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