ATSB finds trim setting led to Essendon crash

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A misset rudder trim was behind the crash of a B200 King Air in Essendon in February 2017, the Australian Transport Safety Bureau has found.

The charter flight crashed shortly after take-off into a shopping centre near Essendon Airport, on 21 February 2017, killing the pilot and four passengers.

‘The pilot did not detect that the aircraft’s rudder trim was in the full nose-left position prior to take-off,’ the ATSB said this morning. ‘The position of the rudder trim resulted in a loss of directional control and had a significant impact on the aircraft’s climb performance in the latter part of the flight.’

From its inspection of the wreckage, the ATSB discovered the rudder trim set to maximum nose left deflection.

‘The rudder trim actuator screw jack was extended 43 mm when measured from the actuator body to the center of the rod end, which equated to the rudder trim being in the full nose-left position,’ the accident report says.

The ATSB found the aircraft’s checklists required the position of the rudder trim be checked five times and the weight and balance of the aircraft be checked once before take-off. It was not clear which of the available checklists for the B200 King Air the pilot used but all require rudder trim to be checked.

The ATSB also found the aircraft was overweight by 240 kg, but this had not had a significant effect on the outcome of the flight. The aircraft’s cockpit voice recorder had been inoperative after a previous flight incident tripped an impact switch on the unit. No pre-existing engine problems were found.

The ATSB said the crash highlighted the importance of having, using and completing checklists.

‘Cockpit checklists are an essential tool for overcoming limitations with pilot memory and ensuring that action items are completed in sequence and without omission. The improper or non-use of checklists has been cited as a factor in some aircraft accidents. Research has shown that this may occur for varying reasons and that experienced pilots are not immune to checklist errors.’

As always, the ATSB emphasised that its findings should not be read as apportioning blame or liability to any particular organisation or individual.

Flight Safety Australia has run several stories on take-off, checklist use, and the factors that can induce errors among experienced and skilled pilots, which would be worth rereading in conjunction with the ATSB’s report on this tragic crash.

10 COMMENTS

  1. Bullshit! I don’t believe their finding for one second! They are looking for a scape goat! I knew Max & I too have 1000’s of hrs on the B200, even with full rudder trim set the machine would be controllable otherwise it would not have gotten certification! ATSB ought to be ashamed of themselves!!

  2. I understand your extreme disfaction on this report as I’ve been in the same situation more than once in my flying career. However what else do you suggest could be the likely cause?

    • I don’t have the answer Peter W but I refuse to accept their version of events! Max had a zillion Hrs on type & sure that doesn’t absolve him from making mistakes deliberate or otherwise (there wouldn’t be a pilot out there who hasn’t ticked every box so to speak before every flight) but the incorrect setting of a rudder trim or not picking it up as not set for T/off is more a rooky mistake than a highly experienced person on type. In all the years on type I never moved any of the trims to the full travel (cause that alone is lining up a swiss cheese hole) so unless there was some maint action prior to that flight involving the trim movement to that extreme & left there then something doesn’t add up here & the ATSB found an easy out ! Again disgraceful!

  3. How about some correcting rudder input …the tab is fine control ..not primary control. The report sounds very sus unless the pilot had health issues and was unable to correct the tab drift..

  4. I agree the finding on rudder trim only is highly unlikely and I couldn’t make sense of it until I read another extract of the report where it stated: “The ATSB also noted that the aircraft did not have flaps set at the time of impact. It was normal practice to use approach flaps for take-off, and the ATSB thought that although it was possible they were retracted after take-off, it was considered highly unlikely due to the short time between rotation and the crash.”

    240kg over MTOW and no flaps would explain the long TO roll and poor performance once airborne. The rudder trim would then be a contributor to the factors that brought this aircraft down.

    • Brian, it is good to see that there are experienced aviators still able to ‘critically analyse the factual information’. Biased and emotive terms such as ‘They are looking for a scape goat! and ‘I don’t have the answer Peter W but I refuse to accept their version of events! will do very to advance aviation safety. Remember more experienced swimmers drown each year in Australia, than inexperienced swimmers. The number of hours in a cockpit will never negate the need for checklist as each of us (regardless of experience) still have human limitations, that’s the reason why we need and use checklists isn’t it?

  5. I believe if the rudder trim was hard over he would have had one hell of a time holding it on the centre line of the runway half way through his take of roll and with his experience aborted the take of .

    A simular error was made in the initial finding of the Partenavia crash at Essendon, but in that crash the pilots survived and were able to debate the finding and prove it wrong.
    Laurie.

  6. As an experienced pilot with Check & Training approval on type I find the ASTB investigating of this accident lacking in depth..In particular what was the pilots seat position at the time of the accident? Did they check the witness marks on the seat rails after the accident?
    If they had they could have found whether or not the pilot was physically capable of applying the necessary amount of of rudder to retain directional control.
    My experience shows that most experienced pilots undergoing an asymmetric check do not have their seat positioned correctly to achieve full rudder deflection.
    On B200 training flights I always demonstrated the need to have the seat further forward than was initially thought necessary as this is a peculiarity of, but not limited to, this type.
    If this were the case (and we will never know unless ASTB has done it’s work properly) the pilot would have been using excessive aileron in an attempt to maintain directional control.
    The predictable result with the extra drag would have been a significant loss of performance.
    Ask any experienced B200 pilot and they will tell you that despite the offset trim, the 240Kg overload and no flaps. If that aircraft was flown with the ball in the center at the correct attitude there would have been a positive climb rate.
    Until the ASTB come up with verified evidence of the seat position at the time of the accident no one can be blamed for not accepting their findings fully.
    They have come up with findings but it’s not the full story.
    This hypothesis is supported by other experienced B200 Check & Training Pilots and I have been encouraged to make this statement.

    AN INDEPENDENT STATEMENT ON THE ABOVE BY AN EXPERIENCED B200 C&T PILOT
    I totally approve your comments!
    Additionally, to prove a point, this can be a proven possibility, both on the ground firstly,
    and secondly, in flight without compromising safety, by demonstrating
    factually, what can happen if. (a) The seat position was not in the ideal position.
    (b) The rudder pedals were not adjusted correctly.
    (c) If the seat for whatever reason was to slip back
    to the rear safety stop, it is impossible for a pilot
    (depending on height) to keep directional control
    and maintain pitch control.
    (d) Also there is no way to pull oneself forward ( depending on
    the seat height adjustment) if the seat is at the full aft
    track limiting stop.

    (e) If the seat were to slip back on rotate, the pilot cannot
    reach the now pulled back throttles for correct power
    adjustment?
    (f) A weakness in the B200 is if a large amount of rudder pressure force is required and, even if the seat is in a normal position, the pilot naturally forces himself, up the seat back reducing his rudder authority.

    On the final report as I see it, full offset rudder trim is not conclusive in total, as the aircraft
    when certified under Part23/25 for B200, should still have been controllable?

    More so it appears that investigators were initially suspecting engine failure on the LH engine,
    but should have been looking at witness marks on seat track’s, seats possible position of
    rudder pedals etc. i.e. Looking at overall contributing factors?
    I cannot cover in depth overall, but I believe this was a possible scenario In the case of the Essendon accident.
    I was disappointed that my two phone calls offering assistance did not deserve a reply.

    (Name available on application)

  7. Thank you, Ian, for the invitation to ‘take note’ of those additional comments by (name not supplied), regarding the accident report for VH-ZCR at Essendon.

    Over the years I have resisted the desire to reply to comments or criticisms of a particular investigation finding/s as often these criticisms were:

    (a) just not credible as they often ‘fly in the face of simple physics’ or:
    (b) or they were so emotive and lacking in objectivity that a reader could be excused for thinking they were payback for some perceived wrong doing by a previous investigation or investigator.

    My background: I have been an aviation accident investigator with BASI/ATSB for 25 years (now semi- retired). Having attended more than 185 on site investigations and participated in more than 200 lesser accidents and or serious incident investigations.

    Gentlemen, I respectfully ask that you accept my word for the fact that on every occasion that I have attended at an accident event the investigation team attempted to the best of their ability to thoroughly examine all levels of available evidence (physical, factual, witness circumstantial and even hearsay) to determine possible contributing factors. Firstly, investigators gather as much physical and factual evidence as possible, this evidence then frames the investigation (remember evidence has a hierarchy). Following this, they conduct critical analysis (not emotive) of that factual information before making any relevant or necessary safety notice or recommendations.

    Notwithstanding, what some commentators believe, the investigators have no agenda other than to enhance aviation safety. In conducting an investigation, the only assumption (if you can call it that) they will make, is the belief that the pilot or person involved did not want or expect an accident outcome. Therefore, the investigation focuses, not only finding out what, where, when and how but as much as reasonably possible why it happened?

    Before leaving any accident site, team members will always discuss and refer to their detailed check lists, which have continued to be refined and updated over many decades. The team is organised throughout on this basis. Remember investigators too are drawn from experienced pilot and engineering backgrounds and are very aware of the importance of check lists.

    Comments regarding the seat rails.

    Over the years I have attended at least 2 ‘loss of control after take-off’ investigations where there was clear ‘physical’ evidence that the seat adjustment locking pin had allowed the pilot seat to move rearward at take-off. However, on several other occasions it was not possible to make this determination with any certainty due to impact and fire damage. As you are aware the seat rails are extruded aluminium alloy which melt relatively easily if there is a post impact fire.

    I note that while the official report did not specifically advise examination of the seat rails, on page 34 of the report it did state: ‘The majority of the aircraft was damaged or destroyed as a result of the collision with the building and subsequent fire. The damage precluded a complete examination of many components and systems.’ Figure 28 of the report also shows the extent of the fire and impact damage.

    While it is obvious that no investigation can provide answers for all possible post-accident hypotheses, opinions or theories (as so many are just not credible when compared to the known physical or factual information) please accept that investigators do consider and collect all available evidence as objectively and impartially as possible.

    (name not supplied) your comment

    (c) If the seat for whatever reason was to slip back to the rear safety stop, it is impossible for a pilot
    (depending on height) to keep directional control and maintain pitch control.

    (d) Also, there is no way to pull oneself forward (depending on the seat height adjustment) if the seat is at the full aft track limiting stop

    In answer to your comment

    I agree with your statements; however, I would again respectfully suggest another analysis of this evidence.

    If pitch control was lost due to the pilot’s seat sliding backwards, what significant evidence would you expect to see following such an even? Irrespective of roll and yaw, at the very least, I would expect it would result in a sudden pitch up followed by a steep climb of at least some duration, due to the pilot having the controls in his hands and not enough time or forward authority to counter the pitch up caused by him sliding rearwards and taking the control column with him? Surely this would be more of a probability than just a possibility? In such an event I would reasonably expect evidence of a continuing steep climb situation, possible even followed by a stall, if the pilot was not able to get forward. This was certainly the case in both previous investigations where we were able to confirm loss of control due to the pilots seat track not being locked. This does not appear to be the evidence for the Essendon accident.

    Regarding pitch axis, the report advised that for the Essendon event, both the recorded and witness evidence indicated only a slow climb before descending?

    From the official report:

    ‘At rotation, a witness familiar with the aircraft type observed a yaw to the left followed by a
    relatively shallow climb.’ A reduction in left engine power would have exacerbated the left yaw, however, this was discounted as the key witnesses reported that the engine/s sounded normal and the ATSB’s
    dashboard camera audio frequency analysis detected no change in engine sound. In addition,
    engine and propeller impact evidence support the left engine producing take-off power at impact.
    There was no evidence to indicate that the left yaw was the result of an asymmetric engine power
    condition.’

    While the lack of evidence of a sudden pitch up or steep climb by itself cannot be taken to prove that the pilot’s seat did not slide rearwards, it is certainly reasonable to expect to see a more significant departure from controlled flight than appears to have occurred because as you say in
    (c) ‘it is impossible for a pilot (depending on height) to keep directional control and maintain pitch control’.

    Gentlemen, again I respectfully suggest that you both may be over focusing on the possibility of a seat rail event to the exclusion of the more substantive evidence provided in the official report.
    There are often several contributing factors that come together to make an accident. The definition of a contributing factor being:
    ‘Contributing factor: a safety factor that, had it not occurred or existed at the time of an occurrence, then either:
    a) the occurrence would probably not have occurred; or
    b) the adverse consequences associated with the occurrence would probably not have occurred or have been as serious, or
    c) another contributing safety factor would probably not have occurred or existed’

    During my time as an investigator I have always welcomed constructive criticism (as I am sure most investigators do). To me it meant that people were concerned enough about safety to be involved. But I do believe that criticism has to be constructive and not destructive. Subjective or overly emotive comments can be divisive and counterproductive to safety outcomes.

    Bob Kells

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