Tactful of toothless?
Hi Sidebar; welcome. We too are waiting (quite a long wait) for the Pel-Air report. It promises to be an ‘interesting’ study piece. My ‘tote’ board has a record number of entries and, the written forecast results are very ‘entertaining’. Top money is for release on or about ‘Budget’ day. We shall see. But today we have the ATR incident to consider.
The ATSB report, although a long time arriving, is better stuff. This is what we may expect from a ‘deep’ investigation with the manufacturer involved and confirmation from the UK supports the ATSB conclusions; however. Do the SR’s make good sense? Are you prepared to by-pass the radical causes?
ATSB: “The pitch disconnect occurred while the crew were attempting to prevent the airspeed from exceeding the maximum permitted airspeed (VMO)”.
ATSB – “The ATSB recommends that EASA monitor and review ATR’s engineering assessment of transient elevator deflections associated with a pitch disconnect to determine whether the aircraft can safely withstand the loads resulting from a pitch disconnect within the entire operational envelope. In the event that the analysis identifies that the aircraft does not have sufficient strength, it is further recommended that EASA take immediate action to ensure the ongoing safe operation of ATR42/72 aircraft.”
But what of the crew actions which had the aircraft at ‘red line’, the conflicted elevator inputs which created the disconnect of the elevator channels and subsequent damage, caused by operations outside the ‘certified’ design envelope? Why are these elements not examined, in detail, before questioning the ‘integrity’ of the manufacturer and the certifying agency?
Limitations and certification tests, must, if aircraft are to fly, have ‘limits’ and then a ‘buffer’ about those limits which can be ‘reasonably’ supported. Simplistically put, an egg is ‘designed’ and tested to withstand certain anticipated loads, if it is a government certified egg, then if will be required to withstand that load + a ‘reasonable %’ more. Used correctly, your egg will last, throw it a wall with no more than that % above ‘test’ all is well. Go past that limit and you have a clean up job to do. The point I’m trying to make is if an airframe is ‘thrown’ at a wall, above the limitations imposed, something will break. The ATR is a proven, might tough airframe; the fact that it failed to ‘break’ during the initial incident and continued operations for quite a while afterwards, speaks well for design and certification standards. What is not being addressed by the ATSB is ‘how’ the initial damage was done; and, what caused it. Why is this element being so carefully stepped around? ATR cannot continue to increase allowable limits to an infinite value, on ATSB say so. It is an aircraft, not the harbour bridge.
I did at one time do the research into the force required to ‘separate’ the control channels; can’t find it now, but it was a significant number i.e. you have to really mean it. One pulls back, the other pushes forward, the clutch disengages and you have independent elevator controls. So, somehow, even accidentally, the conflicting crew ‘actions’ have managed to not only separate the control channels, but, through opposing forces, imposed a greater load on the airframe than certification design specifications.
There may well be a ‘design’ and ‘certification’ weakness; but provided the aircraft met the certification requirements, as specified, and has been proven to exceed those specification through ‘hard’ use, then is it fair to question the integrity of the aircraft – as presented?
Another troubling part of this ATSB report is the lack of FDR and CVR data. I, for one, would very much like to know exactly what occurred on the flight deck and see the exact data provided by the FDR. In particular, the pitch channel and speed data for the entire sector. I wouldn’t mind seeing the original written reports from both aircrew and engineering either.
Vitesse (not velocity) Maximum Operating. (Vmo). Maximum Operating limit speed. Red line…
FAA - The pilot should be aware of the symptoms that will be experienced in the particular airplane as the VMO or MMO is being approached. These may include:
• Nose-down tendency and need for back pressure or trim.
• Mild buffeting as airflow separation begins to occur after critical Mach speed.
• Activation of an over-speed warning or high speed envelope protection.
Personally, I can’t remember ever pushing an airframe to the ‘red line’ as a regular practice; often close, but not deliberately to, for several reasons; gas for Mum, speed for the kids and height for my own peace of mind is always in the flight bag. I digress.
When this incident occurred, there were some good post on the UP related (some rubbish as well) but for those who would like to take their thinking beyond the narrow confines of the ATSB report; start –HERE -.
Good, but incomplete, ATSB marked 4 out of a possible ten, which is much better than the usual 1 or 2 they struggle to win. Although the following, carefully read, is a typical, ATSB conflicted nonsense.
The ATSB recommends that EASA monitor and review ATR’s engineering assessment of transient elevator deflections associated with a pitch disconnect to determine whether the aircraft can safely withstand the loads resulting from a pitch disconnect within the entire operational envelope. In the event that the analysis identifies that the aircraft does not have sufficient strength, it is further recommended that EASA take immediate action to ensure the ongoing safe operation of ATR42/72 aircraft.
To what limits? It already meets the prescribed and proven better, so, what's the point?
For analysis of the inflight situation, ATR has used the aerodynamic model that was developed during certification. Preliminary results for the jamming scenarios was provided. Those results showed that the inflight system response is also that of an underdamped oscillatory system. It also indicates that the magnitude of the system response is dependent upon the pilot input to the control column, and how quickly the flight crew respond to PUM activation. The system has margin for jams at the elevator. ATR are continuing the analysis of jams at the control column.
Again, how long is a piece of string? Is it a King Kong v Faye Wray tussle or two average pilots pulling and shoving? Balanced, I don't think so.
The ATSB acknowledges the efforts of ATR to resolve the safety issue. The ATSB also notes that, while the short term risk assessment does not account for the transient elevator deflections associated with a pitch disconnect, until the results of the detailed engineering analysis are available it is not possible to accurately quantify the transient elevator loads. Consequently, it is not possible to fully determine the magnitude of the risk associated with continued operation of ATR42/72 aircraft until the engineering analysis is complete.
Noting the above, the ATSB’s retains a level of ongoing concern as to whether the aircraft has sufficient strength to withstand the loads resulting from a pitch disconnect. Consequently, while the ATSB accepts that the current level of safety action partially addresses the safety issue; the ATSB makes the following safety recommendations.
Somebody, anybody, please: explain what that last load of double speak bollocks means.
Toot – sigh – toot.
Hi Sidebar; welcome. We too are waiting (quite a long wait) for the Pel-Air report. It promises to be an ‘interesting’ study piece. My ‘tote’ board has a record number of entries and, the written forecast results are very ‘entertaining’. Top money is for release on or about ‘Budget’ day. We shall see. But today we have the ATR incident to consider.
The ATSB report, although a long time arriving, is better stuff. This is what we may expect from a ‘deep’ investigation with the manufacturer involved and confirmation from the UK supports the ATSB conclusions; however. Do the SR’s make good sense? Are you prepared to by-pass the radical causes?
ATSB: “The pitch disconnect occurred while the crew were attempting to prevent the airspeed from exceeding the maximum permitted airspeed (VMO)”.
ATSB – “The ATSB recommends that EASA monitor and review ATR’s engineering assessment of transient elevator deflections associated with a pitch disconnect to determine whether the aircraft can safely withstand the loads resulting from a pitch disconnect within the entire operational envelope. In the event that the analysis identifies that the aircraft does not have sufficient strength, it is further recommended that EASA take immediate action to ensure the ongoing safe operation of ATR42/72 aircraft.”
But what of the crew actions which had the aircraft at ‘red line’, the conflicted elevator inputs which created the disconnect of the elevator channels and subsequent damage, caused by operations outside the ‘certified’ design envelope? Why are these elements not examined, in detail, before questioning the ‘integrity’ of the manufacturer and the certifying agency?
Limitations and certification tests, must, if aircraft are to fly, have ‘limits’ and then a ‘buffer’ about those limits which can be ‘reasonably’ supported. Simplistically put, an egg is ‘designed’ and tested to withstand certain anticipated loads, if it is a government certified egg, then if will be required to withstand that load + a ‘reasonable %’ more. Used correctly, your egg will last, throw it a wall with no more than that % above ‘test’ all is well. Go past that limit and you have a clean up job to do. The point I’m trying to make is if an airframe is ‘thrown’ at a wall, above the limitations imposed, something will break. The ATR is a proven, might tough airframe; the fact that it failed to ‘break’ during the initial incident and continued operations for quite a while afterwards, speaks well for design and certification standards. What is not being addressed by the ATSB is ‘how’ the initial damage was done; and, what caused it. Why is this element being so carefully stepped around? ATR cannot continue to increase allowable limits to an infinite value, on ATSB say so. It is an aircraft, not the harbour bridge.
I did at one time do the research into the force required to ‘separate’ the control channels; can’t find it now, but it was a significant number i.e. you have to really mean it. One pulls back, the other pushes forward, the clutch disengages and you have independent elevator controls. So, somehow, even accidentally, the conflicting crew ‘actions’ have managed to not only separate the control channels, but, through opposing forces, imposed a greater load on the airframe than certification design specifications.
There may well be a ‘design’ and ‘certification’ weakness; but provided the aircraft met the certification requirements, as specified, and has been proven to exceed those specification through ‘hard’ use, then is it fair to question the integrity of the aircraft – as presented?
Another troubling part of this ATSB report is the lack of FDR and CVR data. I, for one, would very much like to know exactly what occurred on the flight deck and see the exact data provided by the FDR. In particular, the pitch channel and speed data for the entire sector. I wouldn’t mind seeing the original written reports from both aircrew and engineering either.
Vitesse (not velocity) Maximum Operating. (Vmo). Maximum Operating limit speed. Red line…
FAA - The pilot should be aware of the symptoms that will be experienced in the particular airplane as the VMO or MMO is being approached. These may include:
• Nose-down tendency and need for back pressure or trim.
• Mild buffeting as airflow separation begins to occur after critical Mach speed.
• Activation of an over-speed warning or high speed envelope protection.
Personally, I can’t remember ever pushing an airframe to the ‘red line’ as a regular practice; often close, but not deliberately to, for several reasons; gas for Mum, speed for the kids and height for my own peace of mind is always in the flight bag. I digress.
When this incident occurred, there were some good post on the UP related (some rubbish as well) but for those who would like to take their thinking beyond the narrow confines of the ATSB report; start –HERE -.
Good, but incomplete, ATSB marked 4 out of a possible ten, which is much better than the usual 1 or 2 they struggle to win. Although the following, carefully read, is a typical, ATSB conflicted nonsense.
The ATSB recommends that EASA monitor and review ATR’s engineering assessment of transient elevator deflections associated with a pitch disconnect to determine whether the aircraft can safely withstand the loads resulting from a pitch disconnect within the entire operational envelope. In the event that the analysis identifies that the aircraft does not have sufficient strength, it is further recommended that EASA take immediate action to ensure the ongoing safe operation of ATR42/72 aircraft.
To what limits? It already meets the prescribed and proven better, so, what's the point?
For analysis of the inflight situation, ATR has used the aerodynamic model that was developed during certification. Preliminary results for the jamming scenarios was provided. Those results showed that the inflight system response is also that of an underdamped oscillatory system. It also indicates that the magnitude of the system response is dependent upon the pilot input to the control column, and how quickly the flight crew respond to PUM activation. The system has margin for jams at the elevator. ATR are continuing the analysis of jams at the control column.
Again, how long is a piece of string? Is it a King Kong v Faye Wray tussle or two average pilots pulling and shoving? Balanced, I don't think so.
The ATSB acknowledges the efforts of ATR to resolve the safety issue. The ATSB also notes that, while the short term risk assessment does not account for the transient elevator deflections associated with a pitch disconnect, until the results of the detailed engineering analysis are available it is not possible to accurately quantify the transient elevator loads. Consequently, it is not possible to fully determine the magnitude of the risk associated with continued operation of ATR42/72 aircraft until the engineering analysis is complete.
Noting the above, the ATSB’s retains a level of ongoing concern as to whether the aircraft has sufficient strength to withstand the loads resulting from a pitch disconnect. Consequently, while the ATSB accepts that the current level of safety action partially addresses the safety issue; the ATSB makes the following safety recommendations.
Somebody, anybody, please: explain what that last load of double speak bollocks means.
Toot – sigh – toot.