Old but interesting GV incident
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Old but interesting GV incident
Feb. 14, 2002 West Palm Beach, Florida, U.S. Gulfstream V
Soon after departure, the flight crew requested clearance to return to the airport because the landing gear had not retracted on
command. As the airplane was flared for landing, the ground spoilers deployed. The airplane landed hard, and the right-main landing gear
collapsed. The report said that wooden sticks were found in the weight-on-wheels switches for both main landing gear. The airplane was
on jacks for a tire change when a maintenance technician used the sticks to disable the weight-on-wheels system so that he could access
the maintenance-data-acquisition unit to check an overspeed message. The sticks were not removed after maintenance was completed.
As a result, the airplane remained in ground mode, and the ground spoilers deployed when the crew moved the throttle levers to idle
during the flare.
Soon after departure, the flight crew requested clearance to return to the airport because the landing gear had not retracted on
command. As the airplane was flared for landing, the ground spoilers deployed. The airplane landed hard, and the right-main landing gear
collapsed. The report said that wooden sticks were found in the weight-on-wheels switches for both main landing gear. The airplane was
on jacks for a tire change when a maintenance technician used the sticks to disable the weight-on-wheels system so that he could access
the maintenance-data-acquisition unit to check an overspeed message. The sticks were not removed after maintenance was completed.
As a result, the airplane remained in ground mode, and the ground spoilers deployed when the crew moved the throttle levers to idle
during the flare.
It's bad enough when engineers leave switches out of the usual position in the flight deck - this is more concerning!
Are the WOW on a GV readily visible on a walkaround?
Are the WOW on a GV readily visible on a walkaround?
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other way round, a/c was jammed to ground mode by these sticks.
The airplane was
on jacks for a tire change when a maintenance technician used the sticks to disable the weight-on-wheels system
on jacks for a tire change when a maintenance technician used the sticks to disable the weight-on-wheels system
As a result, the airplane remained in ground mode, and the ground spoilers deployed when the crew moved the throttle levers to idle
during the flare.
during the flare.
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Engineers leaving switches in the wrong positions??
So what is the checklist for??
Lolly sticks left in the squat switches, a proper preflight inspection would have picked this up.
Tony
So what is the checklist for??
Lolly sticks left in the squat switches, a proper preflight inspection would have picked this up.
Tony
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Engineers leaving switches in the wrong positions??
So what is the checklist for??
So what is the checklist for??
Lolly sticks left in the squat switches, a proper preflight inspection would have picked this up.
They paid bitterly for their mistake/apperently not to good walkaround. But lets be honest, these things can happen...
A very experienced pilot once told me: the airplane is only dangerous at 2 times: when it goes to maintenance and when it comes out of it... I try to make the best from this advise.
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Older incident indeed, they were teaching that story at FSI Savannah in 2000 I think)))
The point of the story however is that while it CAN happen that you get airborne and the WOW system still thinks it's on the ground, proper checklist work IN FLIGHT, even for a quick return, would have saved the day.
- Disarming the spoilers is on the "after take-off" as well as the "pattern" checklist.
- checking the AIR or GROUND mode is a part of verifying gear position in the "before landing" check.
Quick decisions, yes. Cutting corners, NO
The point of the story however is that while it CAN happen that you get airborne and the WOW system still thinks it's on the ground, proper checklist work IN FLIGHT, even for a quick return, would have saved the day.
- Disarming the spoilers is on the "after take-off" as well as the "pattern" checklist.
- checking the AIR or GROUND mode is a part of verifying gear position in the "before landing" check.
Quick decisions, yes. Cutting corners, NO
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Yes, an old but interesting incident, invariably discussed in every Gulfstream initial class, GII through GV and in many recurrent classes as well.
Even prior to this accident most experienced Gulfstream operators, myself included, have always made the following call outs with the landing checklist,
"Three green, no red, 3 in air mode, spoilers armed"
I still make the same check on the 650 even though the checklist does not require it ("4 in air mode" in this case).
I've also added a "Bedford" check to the line up checklist to verify free movement of the flight controls.
Even prior to this accident most experienced Gulfstream operators, myself included, have always made the following call outs with the landing checklist,
"Three green, no red, 3 in air mode, spoilers armed"
I still make the same check on the 650 even though the checklist does not require it ("4 in air mode" in this case).
I've also added a "Bedford" check to the line up checklist to verify free movement of the flight controls.
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Bedford check basically covered in the lineup checklist in note between item 5 and 6. " at 60 knots the pilot shall confirm that the elevators are free and the yoke has reached the neutral position".
Avoid imitations
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Engineers leaving switches in the wrong positions??
So what is the checklist for??
So what is the checklist for??
But don't engineers also have a post maintenance checklist?
Lolly sticks left in the squat switches, a proper preflight inspection would have picked this up.
Tony
Tony
But a checklist doesn't necessarily cover the situation where non-controlled and/or unauthorised tools or procedures have been used during maintenance and items left in out of the way places. Even if lolly sticks were/are the correct and controlled tools for the job, why did the engineer leave them in place after maintenance? See above question about engineers' post maintenance checklists. What about proper engineering oversight / quality control?
In the past, I was in a situation where the chief engineer of a major UK maintenance company, under contract for quite a large fleet of RAF aircraft, complained about we pilots. In his opinion we were doing "too thorough" pre-flight walk-round inspections before taking our aircraft away after deep maintenance. In his opinion, it undermined the integrity of his company and was disrespectful to his engineers. He made a pompous and angry phone call to our boss after a colleague of mine picked up his aircraft from them, after they had watched him do his pre-flight.
On landing back at base from that flight the pilot reported that the ASI had come loose and the engine RPM gauge fell out of the instrument panel.
Faults like these were so common with that particular contractor that our base engineers opened an A4 sized book specifically to record them. I saw the book, it had many pages of defects found after the aircraft returned to us, some of them quite serious. Not surprisingly, the contract wasn't renewed.
But a checklist doesn't necessarily cover the situation where non-controlled and/or unauthorised tools or procedures have been used during maintenance and items left in out of the way places. Even if lolly sticks were/are the correct and controlled tools for the job, why did the engineer leave them in place after maintenance?
The tool in question is a wedge-shaped piece of metal which slides between the roller on the base of the squat (nutcracker) switch plunger and the curved metal bracket where the roller normally rides when the gear is compressed. The wedge has a large red "Remove Before Flight" streamer attached to it.
The incident in question was a failure on the part of both the maintenance organization, and the flight crew.
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JRB,
I guessed as much.
But please explain how, bearing that in mind, the flight crew were found to be at fault.
Sticks are definitely not the proper or approved method to put the switches in ground mode.
But please explain how, bearing that in mind, the flight crew were found to be at fault.
However, a flight crew member's specific responsibility during a pre flight walk around is not prescribed in a "regulatory" sense. The AFM provides a guidelines for things that the crew "should" look for... But "should" is not the same as "shall" when it comes to enforcement actions by authorities following an incident. I do know that current Gulfstream AFMs DO specify that the crew should look at the nutcracker switches during a preflight walk around - but I don't know if that was the case in 2002 when the accident occurred.
At the very least, I would like to think that a professional and conscientious pilot would want to look closely at the tires for obvious signs of wear, cuts, under-inflation etc... As well as obvious signs of leaking hydraulic fluid from the brakes, proper extension of the struts etc. To be fair though, on a Gulfstream, all of the these items are most easily seen from the rear of the main gear, while standing behind the trailing edge of the wing - so I can't say that the crew was negligent for not spotting the sticks in the nutcracker switches.
The flight crew's fault in the incident comes from their failure to follow the procedures clearly spelled out in the AFM for an actual or suspected failure of the weight-on-wheels system while in flight. In addition to the inability to retract the gear after takeoff, the crew would have seen other EICAS messages and warning lights that would have indicated the aircraft was still in ground mode.
The crew would ordinarily press a switch just before beginning the takeoff roll to arm automatic deployment of the ground spoilers in the case of an abort. Their very first AFM-mandated action in the case of a suspected WOW system failure after takeoff is to turn the ground spoiler arm switch OFF. They failed to do this. As I recall from reading the final report on the accident, post-crash interviews of the crew, and CVR transcripts showed that the crew did not refer to the QRH emergency procedures at all - they just reported to the tower that they had a gear retraction problem, and requested clearance to come back around for a landing - which they did. Of course, when they pulled the power levers back to idle to flare, the spoilers deployed, and the bottom dropped out. The aircraft was still about 50 feet in the air when the boards came up.
So, if the maintenance crew had not used an unauthorized ad hoc technique to bypass the WOW, system, the accident would not have happened. On the other hand, if the flight crew had followed the AFM procedures for a WOW system failure in flight, that too would have prevented the accident.
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control check
Gulfstream did NOT introduce that check after Bedford, but instead re-emphasized it. I was taught the check and it was in the manuals and checklists long before the Bedford accident.
Just helping to be clear.
Just helping to be clear.
