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Virgin flew for 5 days with damage?


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http://www.atsb.gov.au/publications/investigation_reports/2014/aair/ao-2014-032.aspx

 

The aircraft manufacturer’s job card for a turbulence inspection specified a general visual inspection of the fuselage, stabilisers and wings with more detailed inspections if any anomalies were found. A detailed inspection of the wing attachment fittings was also required irrespective of the results of the general visual inspection.

 

Over the course of the evening the non-rostered engineer and one of the duty engineers worked on disassembling some of the aircraft interior to access the wing attachment fittings. The duty engineers left at 2200, leaving the non-rostered engineer to complete the task. At about 2300 the engineer borrowed a nearby stand to provide a platform at about wing height. While on the stand positioned behind the left wing near the fuselage, the engineer inspected the upper surface of the wing, rear fuselage and tail by torchlight. The engineer finished work shortly after and returned to work at 0600 the next morning.

 

No defects were identified from any of the inspections and the aircraft was returned to service the next day.

 

Suspected birdstrike

 

Subsequent to the occurrence on 20 February, the aircraft was operated on 13 sectors, the last of which was a scheduled passenger flight from Sydney to Albury, NSW on 25 February 2014. On descent into Albury the aircraft passed in close proximity to birds, which alerted the captain to the possibility of a birdstrike. There were no indications that a bird had struck the aircraft but on the ground, the aircraft’s pitch trim system fluctuated abnormally.

 

The captain conducted a walk-around inspection with an expectation of bird damage to the left side of the aircraft. The only abnormality found was a deformity to a fairing at the top leading edge of the vertical stabiliser, which might have been the result of a birdstrike. The captain advised maintenance watch who dispatched an engineer to inspect the aircraft.

 

The engineer used scissor lift equipment to inspect the tailplane and confirmed that the fairing might have been damaged by a bird but that there was also significant structural damage on top of the tailplane. The aircraft was grounded and the ATSB advised.

 

 

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Interesting that each pilot was able to control each half of the elevator independantly in the inital incident.According to the media anyway.

That was according to the atsb. Seems interesting maybe someone can shed some light on that?

 

 

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useful capability to have.......in the event of aileron lock out use elevons....F111's had these, for example (not each crew member controls 1/2 the elevator) bu that roll control drove each side independent of the other side. Perhaps simply a built in redundancy feature

 

 

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ATSB Report: Investigation: AO-2014-032 - Flight control event involving an ATR72, VH-FVR, 47 km WSW Sydney Airport, NSW on 20 February 2014

 

I was also really surprised to read that independent (split) elevator control for each yoke was a safety feature of the ATR72 (also the Dash8, apparently) available under certain circumstances.

 

So I went a googlin' to satisfy curiosity. (some results here attached)

 

I discovered that - as Andy says - it's there as an emergency measure in case of other control surfaces being disabled.

 

Still, I'd have thought there was a need of another level of protection to obviate this (quite imaginable) outcome. From my amateur perspective, anyway, it's hard to think of a quicker way to wreck your tail feathers than having one side going up and the other down, especially at speed up on a T.

 

Anyway it's informative what the experts are saying on Pprune (quote below). I also chanced upon a detailed article comparing the ATR72 and the Q400 which mentions this feature (quote at bottom).

 

This comparison of the two types is a fascinating read in light of this ATR72 event coming together with the report on the 2011 Dash8 accident near Madang (released yesterday by PNG's Accident Investigation Commission).

 

AirlinesPNG DHC-8-103 P2-MCJ accident final report:

 

http://www.aic.gov.pg/pdf/P2-MCJ%20AIC11-1010%20Final%20Report.pdf

 

VIRGIN ATR72 incident …

 

http://www.pprune.org/australia-new-zealand-pacific/538156-virgin-atr-grounded-albury-8.html

 

"FlexibleResponse" wrote:

 

"An explanation of the how the damage occurred is inferred, but not clearly explained in the updated ATSB Report IMHO. From the report, it would appear that one pilot (Capt) was pulling on the pitch control and the other pilot (FO) was pushing and that opposite load caused the disconnect of the two elevators as per the system design for elevator jams. After the elevators disconnect each pilot still had independent control of his respective side (L/R) elevator only (no elevator jam). The sum of the two pilot's pitch inputs at the time of disconnect and conflict over who was in control resulted in the + g overstress. The flight loads from the asymmetric highly deflected (assumption from high +g loads generated) elevator control surfaces (one elevator up and the other down) at near to Vne also caused excessive loads which resulted in structural damage to both elevators and including their attachments to the horizontal tailplane. In turn the asymmetric loads imparted on the horizontal tailplane gave rise to over design limit loading to the vertical stabiliser attachment and surrounding structure resulting in permanent deformation. Some damage was also done to the rudder. So far no reference has been made to whether or not the vertical stabiliser attachment points to the fuselage have also been damaged...but one would assume that the manufacturer's inspection has cleared that area.

 

The message to aviators from this event so far indicates that a strict handover/takeover of control must always be implemented in SOPs and strictly enforced."

 

Article comparing the Q400 and the ATR72

 

http://theflyingengineer.com/aircraft/proud-to-fly-a-turboprop-q400-vs-atr72/

 

EXCERPT:

 

Another situation that could lead to a partial or full loss of control could be a control surface jam. Both the ATR72 and the Q400 have a provision to disconnect the otherwise linked elevators, allowing for the captain or the first officer to have full authority over their respective, independent elevators. But in case of a control wheel (yoke) jam, ATR pilots have to do with nothing but the rudder and power levers to change the aircraft’s heading. Pilots who experience this during training find it very hard to control the aircraft. The Q400, on the other hand, can disconnect the captain’s controls from the first officer’s, allowing the captain to control the hydraulically operated roll spoilers, and the first officer to control the mechanically linked ailerons. Whichever gets stuck, allows for the other to be used.

 

 

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How on earth the two pilots can put in opposite control inputs is beyond me. This was a major factor in a recent "air crash investigations" episode ... I just can't remember the exact details. This is hardly likely to happen in a Boeing with dual control wheels ... but can easily happen with dual (side mounted) side sticks such as found in Airbus aircraft where the left hand can't see what the right hand is doing.

 

 

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As I understand it from the ATSB prelim report, there may, indeed, have been - in a sudden WTF moment - a case both pilots making opposite pitch commands by way of conventional yokes. But what's extraordinary is that, in this case, it seems an ATR safety system interpreted the anomaly as a jammed control and so - as a back up mechanism - gave each yoke its own half of the elevator. An elegant solution for a correct interpretation. However ...

 

Luckily the outcome was not disastrous but it seems to me to be part of a modern pattern: an all too clever system taking over and catching out pilots at a crucial, sometimes fateful, moment. The 'over elaborate design' hole in the swiss-cheese just waiting to line up with the CRM-problemo one - amongst others.

 

In some ways it reminds me of the 2008 A320 test-flight crash in France:

 

ACI makes the case that if only the all-too-subtle system-warning "revert to manual trim" had've been a big unmissable one

 

then things might have been different for them.

 

 

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You MUST always designate the pilot in control. There must be no doubt at all. Something like" I have control" and the other pilot acknowledges with "YOU have control"...... Nev.

 

 

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