King Air down at Essendon?
What rubbish
sar·casm
[ sahr-kaz- uhm]
NOUN
1. harsh or bitter derision or irony.
2. a sharply ironical taunt; sneering or cutting remark
He was not being serious for gawds sake.
He was not being serious for gawds sake.
Sarcastic? Only partly.
Other posts suggested that it is prudent - do I dare say ‘good airmanship’ - to run the rudder trim through its full range and confirm the correspondence of physical position and indicated position during pre-flight. That suggestion was made in a context that implied the check was not aimed only at confirming the rudder trim is indicating the correct position for take off. The implication was that the check is also aimed at confirming the rudder trim system, including the trim indicator, is working correctly throughout its entire range.
Once you say that the point of that pre-flight action is to confirm that the trim system including the trim indicator is working correctly throughout its entire range, you’re acknowledging that you’re checking to confirm that there have been no random failures or maintenance or other interventions that may have caused the system and the indicator to malfunction. If that’s the point of the check, rather than just looking down and seeing that the rudder trim indicator is indicating neutral, it follows that all of the aircraft’s systems should be checked to the extent of their full functionality to confirm there have been no random failures or maintenance or other interventions that may have caused problems. It therefore follows that the PIC:
- should have run up the engines and operated all of the engine and propellor controls through their full range, then shut down and inspected the engines and propellers
- removed all the inspection panels necessary to confirm that no control cable was fraying
- drained and replenished fuel to confirm that calculated and indicated equaled uploaded, and
- done an aircraft re-weigh to confirm that the loading and CofG data for the aircraft remained accurate.
All aircraft systems and components could suffer random failures or be adversely affected by maintenance or other interventions. What’s so special about the rudder trim system, other than hindsight?
Other posts suggested that it is prudent - do I dare say ‘good airmanship’ - to run the rudder trim through its full range and confirm the correspondence of physical position and indicated position during pre-flight. That suggestion was made in a context that implied the check was not aimed only at confirming the rudder trim is indicating the correct position for take off. The implication was that the check is also aimed at confirming the rudder trim system, including the trim indicator, is working correctly throughout its entire range.
Once you say that the point of that pre-flight action is to confirm that the trim system including the trim indicator is working correctly throughout its entire range, you’re acknowledging that you’re checking to confirm that there have been no random failures or maintenance or other interventions that may have caused the system and the indicator to malfunction. If that’s the point of the check, rather than just looking down and seeing that the rudder trim indicator is indicating neutral, it follows that all of the aircraft’s systems should be checked to the extent of their full functionality to confirm there have been no random failures or maintenance or other interventions that may have caused problems. It therefore follows that the PIC:
- should have run up the engines and operated all of the engine and propellor controls through their full range, then shut down and inspected the engines and propellers
- removed all the inspection panels necessary to confirm that no control cable was fraying
- drained and replenished fuel to confirm that calculated and indicated equaled uploaded, and
- done an aircraft re-weigh to confirm that the loading and CofG data for the aircraft remained accurate.
All aircraft systems and components could suffer random failures or be adversely affected by maintenance or other interventions. What’s so special about the rudder trim system, other than hindsight?
Last edited by Lead Balloon; 11th Oct 2018 at 19:18. Reason: Corrected a typo.
Is checking flight controls for 'full and free movement' not a legal pilot pre-flight responsibility? Buried somewhere in the CAR or CAO or Act of every jurisdiction I ever flew in, this one is up there with ensuring instruments work etc.
Are trims not 'flight controls' , albeit classified as secondary on some types?
In any case every checklist ever written says to check them. Where the FCOM is not specific, 'check' may be open to interpretation, but the word check implies more than a cursory glance. Depends on how one was trained in these matters, I suppose.
Of course it is impractical to check every single item, so much of our trust is with the maintenance people. But flight controls are in the 'easily checked' category, so why wouldn't you?. A whole lot more useful than flicking on landing lights to 'check' them, only to bring them one cycle closer to failure. Yet some pilots are absolutely diligent about this exercise in irrelevance, but can't take a minute to run the trims once a day?
But we are digressing from what we believe could have caused this crash. I certainly subscribe to the mis-set rudder trim theory. Whether or not it was properly checked pre-flight can never be known. Because of its mechanical design the trim wheel is highly unlikely to have moved full scale during the crash, so someone put it there. But all this has already been said.
Are trims not 'flight controls' , albeit classified as secondary on some types?
In any case every checklist ever written says to check them. Where the FCOM is not specific, 'check' may be open to interpretation, but the word check implies more than a cursory glance. Depends on how one was trained in these matters, I suppose.
Of course it is impractical to check every single item, so much of our trust is with the maintenance people. But flight controls are in the 'easily checked' category, so why wouldn't you?. A whole lot more useful than flicking on landing lights to 'check' them, only to bring them one cycle closer to failure. Yet some pilots are absolutely diligent about this exercise in irrelevance, but can't take a minute to run the trims once a day?
But we are digressing from what we believe could have caused this crash. I certainly subscribe to the mis-set rudder trim theory. Whether or not it was properly checked pre-flight can never be known. Because of its mechanical design the trim wheel is highly unlikely to have moved full scale during the crash, so someone put it there. But all this has already been said.
All aircraft systems and components could suffer random failures or be adversely affected by maintenance or other interventions
so much of our trust is with the maintenance people
Had to winch a pilot and his pax out of the water after a ditching because of vibrations (helo). Turned out a component in the rotor head, which had been installed as a new item, obtained from the manufactures distribution centre, was actually time expired and should have been scrapped, but somehow made its way back into the supply chain.
Called early one morning to do a medevac in a helo. The routine was that the aircraft had been pre flighted, prepped etc the previous day, so all the responding crew had to do was pull the bungs, a quick walk around, and get the show on the road. In flight the aircraft had a bit of a vibe and was written up on return. Engineering inspection found that bearings had not been installed on any of the rotor blades. The only way that that was evident was a black powder emanating from where the bearings should have been, the black powder being the result of flying/operating. Without the black powder as a clue you would have had no idea the bearings were missing. So many questions to be asked, duplicate inspections on build up of the rotor head, vibrations during the blade tracking and test flight, pre flight during the prep for the medevac duty - was powder evident? Don't know any of the answers found. And it was not a shoddy organisation when it came to maintenance, quite the reverse in fact, but it highlights how fallible we humans are, or can be.
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"Full free and correct" while helpful is not a guarantee of a controllable aircraft. Same with the external pre-flight inspection.
For the most part, the only time trims are moved all the way to the stops are for such checks.
If, a slipping grub screw or broken cable prevents the return of said tab to the desired setting the crew is unlikely to be any the wiser, given the control position in the cockpit will appear normal.
For the most part, the only time trims are moved all the way to the stops are for such checks.
If, a slipping grub screw or broken cable prevents the return of said tab to the desired setting the crew is unlikely to be any the wiser, given the control position in the cockpit will appear normal.
The only time the trims are moved all the way to the stops in any aeroplane I fly is every first flight of the day. By doing that, one gets a feel for the system and hopefully would notice a change of friction associated with slipping grub screws, broken cables etc. On the walkaround I grab hold of the tabs that I can reach and give them a bit of a waggle to feel for too much play in the actuaters while noting their position relative to the controls in the cockpit. Am I so diligent on every flight? Yep, but I make no claim to being perfect. Other stuff I do gloss over if I perceive it as not likely to kill me..
But, that's just one old man's opinion and practice.
But, that's just one old man's opinion and practice.
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Megan,
What does the B200 AFM say regarding preflight checks/inspection of trim tabs?
Edited to add:
We know what the checklists say. Just interested in what it says for the "walkaround" phase.
What does the B200 AFM say regarding preflight checks/inspection of trim tabs?
Edited to add:
We know what the checklists say. Just interested in what it says for the "walkaround" phase.
Last edited by FGD135; 12th Oct 2018 at 04:37.
As follows FGD
Cockpit/Cabin check - Trim Tabs SET TO "0" UNITS - Caution - The elevator trim system must not be forced past the limits which are indicated on the elevator trim indicator scale, either manually, electrically, or by action of the autopilot.
Left Wing & Nacelle - Aileron and Tab - CHECK
Right Wing & Nacelle - Aileron and Bendable Tab - CHECK
Tail - Rudder, Rudder Tab, Stinger and Static Wicks (4) CHECK
Tail - Elevator, Tab, and Static Wicks (3 each side) CHECK, Verify Tabs are in "0" (Neutral) Position. NOTE - The elevator trim tab "0" (neutral) position is determined by observing that the trailing edge of the elevator trim tab aligns with the trailing edge of the elevator when the elevator is resting against the down stops.
Cockpit/Cabin check - Trim Tabs SET TO "0" UNITS - Caution - The elevator trim system must not be forced past the limits which are indicated on the elevator trim indicator scale, either manually, electrically, or by action of the autopilot.
Left Wing & Nacelle - Aileron and Tab - CHECK
Right Wing & Nacelle - Aileron and Bendable Tab - CHECK
Tail - Rudder, Rudder Tab, Stinger and Static Wicks (4) CHECK
Tail - Elevator, Tab, and Static Wicks (3 each side) CHECK, Verify Tabs are in "0" (Neutral) Position. NOTE - The elevator trim tab "0" (neutral) position is determined by observing that the trailing edge of the elevator trim tab aligns with the trailing edge of the elevator when the elevator is resting against the down stops.
So apparently the PIC did neither the cockpit/cabin check nor the external walk around check, at least not in relation to the rudder trim.
Still no explanation as to how the rudder trim apparently came to be set full NL before the flight. And the performance airborne with two engines producing full power was really poor - puzzling so - even assuming the rudder was trimmed full NL.
Incredible. Really incredible.
Still no explanation as to how the rudder trim apparently came to be set full NL before the flight. And the performance airborne with two engines producing full power was really poor - puzzling so - even assuming the rudder was trimmed full NL.
Incredible. Really incredible.
A little bit of context. It's a very large trim. You'd think it would be hard to miss it. I also note what may be a slight off-set of the rudder to the right, despite the controls appearing to be in a neutral position.
Sincerest apologies if I have the wrong model.
Sincerest apologies if I have the wrong model.
So apparently the PIC did neither the cockpit/cabin check nor the external walk around check, at least not in relation to the rudder trim.
A little bit of context. It's a very large trim. You'd think it would be hard to miss it
The report has not tested this.
They put a guy in a SIM, but he did not fly the accident profile. The SIM flew up to (or slightly over) 140 knots, but the accident aircraft did not get above about 112 knots airspeed (report lists groundspeed).. If the trim condition was the cause of the accident and the SIM flew the accident profile, then the SIM should have a) not got above 112 knots and b) crashed.
The other alternative would be to do what the ATSB did in the last trim related fatal accident at Essendon - the Partenavia. in 1978. In this instance the ATSB flew a real aeroplane in a disciplined test manner and recorded the force required to counteract the elevator trim at different trim settings and airspeed. The results table was part of the report. I would think that a diligent report would have followed the same methodology the ATSB used in the past.
As a result of the Partenavia accident an AD was issued soon after that changed the elevator trim limits. If the out of position rudder trim is so catastrophic and there is a history of other incidents, you would think that some review of the B200 rudder trim might be warranted and mooted in the report.
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If the trim condition was the cause of the accident and the SIM flew the accident profile, then the SIM should have a) not got above 112 knots and b) crashed.
I suspect that, due to the large sideslip angle, the fin would have been fully stalled - thus putting the aircraft outside the envelope.
And you're also not allowing for possible differences in the physical performance of the sim pilot vs the real pilot. This has also been pointed out to you.
... the ATSB flew a real aeroplane in a disciplined test manner and recorded the force required to counteract the elevator trim at different trim settings and airspeed.
Old Akro, you are making the assumption that the sim is a 100% faithful replication of the real aircraft. Myself and several other posters have already pointed out to you that no simulator, of any aircraft, is that accurate - especially when flight "outside the envelope" is involved.
I suspect that, due to the large sideslip angle, the fin would have been fully stalled - thus putting the aircraft outside the envelope.
And you're also not allowing for possible differences in the physical performance of the sim pilot vs the real pilot. This has also been pointed out to you.
I suspect that ATSB policy may not permit them to take a real aircraft outside the envelope. To have done testing with less than full NL trim may not have had sufficient validity - particularly whilst the fin remained unstalled.
I suspect that, due to the large sideslip angle, the fin would have been fully stalled - thus putting the aircraft outside the envelope.
And you're also not allowing for possible differences in the physical performance of the sim pilot vs the real pilot. This has also been pointed out to you.
I suspect that ATSB policy may not permit them to take a real aircraft outside the envelope. To have done testing with less than full NL trim may not have had sufficient validity - particularly whilst the fin remained unstalled.
I suspect that ATSB policy may not permit them to take a real aircraft outside the envelope. To have done testing with less than full NL trim may not have had sufficient validity - particularly whilst the fin remained unstalled.
But, a) simulators are commonly used to reconstruct accident scenarios. Its clear that the ATSB didn't do this. and b) we don't know what they did because they haven't provided any details in the report (unlike for example the Partenavia report). But the SIM flying they did and the conclusions they reached are from airspeeds outside that flown by the accident aircraft and therefore, invalid.
You don't need to fly "outside the envelope" to test a hypothesis and I think the 1978 Partenavia report demonstrates this nicely. in this instance, the ATSB took a real aeroplane that was identical to the crashed one and had a pilot experienced on type fly it. The pilot flew a predetermined flight test that consisted of flying a range of different airspeeds at each of the marked trim settings. The control forces were measured at each airspeed / trim combination. When the pilot approached the limit of comfort of control-ability of the aircraft, he stopped and didn't proceed to the next trim setting / airspeed.
If this testing was possible and warranted for the last trim related fatality, why wouldn't it be now?
A 1 hour flight, 2 brake pedal force transducers, a motec logger and this topic would have been nailed and if it was the smoking gun would have obviated the need for the whole sideslip calculation mess.
The ATSB has not provided any firm evidence either in terms of statements from the manufacturer, interviews with other B200 pilots or flight test data to support its assertion that the aircraft was not controllable with full left rudder trim. If full left rudder trim can be counteracted by foot application of right rudder, then there is another factor at play (which may better fit the long take-off run which the ATSB has conveniently glossed over).
The B200 aircraft certification requires that the pilot is able to counteract full elevator trim. There is no similar requirement for rudder trim, although someone pointed to another requirement that infers this. I would question whether full rudder trim leading to loss of control of the aircraft was diligent "fail safe" deign.
The whole premise of the report is therefore based upon speculation.