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-   -   Gulfstream concedes flaw (https://www.pprune.org/biz-jets-ag-flying-ga-etc/565515-gulfstream-concedes-flaw.html)

tlbrown350 1st Aug 2015 17:53

Gulfstream concedes flaw
 
Deadly failure on the runway

stilton 3rd Aug 2015 03:58

Terrible design.


Boeing Aircraft do not have gust locks.


No need as control surfaces are damped with hydraulic power on and snubbed with power off.

Can't understand why Gulfstream couldn't do the same thing.

JammedStab 3rd Aug 2015 05:13

The old HS748 turboprop has gust locks as well with a similar sort of protection system preventing the throttles from being moved forward simultaneously beyond a certain amount to be used for taxiing(one throttle alone could be moved forward for an engine run).

Apparently there was a case where the lock engaged on the takeoff roll leading to a crash with at least one resulting change being that the pilot had to move the control column back and forth a bit during the takeoff roll to ensure that the elevator was still free. Lack of freedom meant an RTO.

Aside from properly following the checklist, it may not be a bad idea to do this kind of elevator check on any aircraft with gust locks just in case you happened to have some sort of failure as well. Might have alerted this crew to a problem early in the roll.

A higher risk scenario might be in a training scenario where you landed, put locks on, backtracked, takeoff again and forgot to remove the locks combined with these two examples of mechanical protection failure.

Tourist 3rd Aug 2015 08:06

Plenty of aircraft have locks.


Its mostly an example of terrible piloting.

Skipping checks makes it their fault.

JammedStab 3rd Aug 2015 11:00

True. And a good example of why not to rely on warning systems to save the day. Just like the Delta 727 in DFW and Northwest MD-80 in DTW where the flaps were left up and the configuration warning failed to provide a warning.

Have to triple check certain killer items yourself perhaps outside of the checklist.

Global_Global 3rd Aug 2015 11:42

WOW... OK the design is trap waiting to happen at some point. But they only checked the controls twice in full and 16 partially in176 flights??? :sad:

PLovett 8th Aug 2015 11:15

Shortcuts and complacency kill.

glad rag 8th Aug 2015 23:21


Originally Posted by Tourist (Post 9068117)
Plenty of aircraft have locks.


Its mostly an example of terrible piloting.

Skipping checks makes it their fault.

Indeed.

However the real gotcha it that "intermediate" position...........

cockney steve 10th Aug 2015 10:38

Perhaps go backwards to a large red "remove before flight" flag attached to a "key" that operates the gust locks externally Then that same "key" could be designed to release throttle-locks IE it must be inserted and locked in place before throttles could be moved from closed. ?....yep, a ballache, but it would save stupid from itself. )(apart from the danger that some smartass would use a duplicate "key" to unlock the throttles whilst the controls were still locked.

make it idiot-proof, you'll breed a better class of idiot.
These people were killed by complacency.

OFBSLF 11th Aug 2015 19:22

How hard is it to do a control movement and freedom check prior to taking off? Is it really unreasonable to expect a pair of professional aviators to do so prior to taking off?

I'm just an uneducated SLF, but it seems to me that the problem here was the pilots, not the plane. If they had done the control system check, they would have found that the gust lock was still on.

galaxy flyer 11th Aug 2015 22:53

True, OLFSLF, but not doing to checks didn't cause the accident, the gust lock being place did. It's a fine line, but the design caused the accident, the pilots contributed by their negligence and could have averted the outcome by performing the checks.

GF

Astra driver 13th Aug 2015 17:47

All Gulfstream models prior to the G650 utilized a gust lock mechanism, which from personal experience I can say never once presented a problem. It was always very straight forward, follow the checklist; release the gust lock prior to engine start and do the full flight control checks (Which take all of about 5 - 10 seconds) after engine start.

If you read the full transcript of the NTSB report as well as Gulfstream's report on the testing of it's gust lock system you will see numerous references to the handle mechanism being "worn" or "broken". (Physical evidence from the accident airplane shows that the handle was not in the fully down position and the handles that failed to fully protect in the Gulfstream tests were similarly worn.)

I'd say that Gulfstream is not so much conceding that the mechanism is defective, rather they are giving crews a stern warning, follow the procedures in the AFM and checklists.

Gulfstream's newest model, the G650 doesn't use a gust lock and instead relies on hydraulic damping to prevent control surface damage. Interestingly, years of habit of following the "Before engine start" checklist of the previous models still occasionally causes me to reflexively say "Gust-lock, released".

stilton 14th Aug 2015 09:07

'Gulfstream's newest model, the G650 doesn't use a gust lock and instead relies on hydraulic damping to prevent control surface damage'


This is what is standard on transport category aircraft, gust locks are asking for trouble, time to get rid of them !

OFBSLF 24th Aug 2015 17:52


True, OLFSLF, but not doing to checks didn't cause the accident, the gust lock being place did. It's a fine line, but the design caused the accident, the pilots contributed by their negligence and could have averted the outcome by performing the checks.
We're going to disagree on that. IMO, the pilots negligence directly caused the accident. They didn't perform the standard checklist prior to takeoff. If they had, the accident never would have happened.


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