Throttle on idle in order to deploy Reverse, if on air mode no unlock and no deployment. We LJ60 guys know how is our aircraft and the problems with the braking, in any case it was just bad luck, something did not work to stop it, let´s wait for the investigation and learn about it.

I had forgotten this one. You're right I stand corrected.

8 vs 20
 

We only use 20 degrees for wet contaminated and 8 degrees for all other TO's.

Doesn't sound all that daunting...like any take off, I would assume flying a Lear you make sure you have a 'clear panel' before you take off. That said, what would have happened to cause them not enough speed for a lift off, but too much speed to stop the aircraft in an 8700 ft runway? I tend to suspect something that tends to extend getting to V1, a deflating tire..creates drag, increases acceleration distance. It seems to bite those pilots that just sit there and wait and wait for V1, then when they see the runway coming up at the end, obviously well past the V1 runway decision pt, predicated by a normaly working aircraft, they now have no time to stop...nor have or can they accelerate...so they do the best they can. As this happened at night, at an airport they weren't familiar with, probably tired, maybe they just didn't get the visual cues that they were burning up more runway then typical. I find it interesting that V1 runway lenghts aren't published..it might help in this area. The 60/40 rule is very important here. Many airline pilots are taught to proceed with a blown tire. and thus auger the plane off to the scene of the accident(Concord/Africa).in GA planes, the plane may never get off the ground, as only one or two tires per side, vs 1 of 4 or more. Either way it's a bad place to be...too fast and too little runway to stop, not enough speed to fly.

900-7x, please continue with your thoughts.

What if the failed switch would let the aircraft think it is in airborne mode, so the thrust reversers remain in the stowed position. If now pulling on the piggy back levers for the reverser, the reversers will not open. OK so far.

But will the engines remain on idle or will the engines spool up due to the movement of the reverser piggy back levers?

If the engines would spool up (because there is no interlock as stated above), you would actually accelerate the aircraft as the reversers are not deployed. If you at the same time apply max braking you may wear out or overheat the brakes in a few seconds before you recognize the situation.

Getting the reverser piggy backs back to the stowed position would reduce engine power back to idle, but now you would have overheated (=no) brakes, no emergency brakes, no spoilers, no reversers.

Here is another accident with the damaged switch and reversers, how was it possible to create skid marks of 2500 ft when the aircraft should have stopped in 850 ft? Adding of forward thrust during braking could be an option...

(... means some lines deleted to shorten the text)

HISTORY OF FLIGHT
On January 14, 2001, at 1345 central standard time, a Learjet LJ-60, N1DC, collided with two deer during landing and ran off the end of runway 7 at the Troy Municipal Airport, Troy, Alabama. The airplane was registered to and operated by Ark-Air Flight Inc. The business flight was operated under the provisions of Title 14 CFR Part 91 and visual flight rules. Visual meteorological conditions prevailed, and an IFR flight plan was filed. The Airline Transport pilot (ATP) and ATP rated first officer received serious injuries, and the airplane was destroyedand there was a post-impact fire. The flight originated from Love Field in Dallas, Texas, at 1030 on January 14, 2001.

According to witnesses, the airplane collided with the deer shortly after touchdown and continued down the runway with the tires smoking, and veered off the right side of the runway near the end, crossed a taxiway, and impacted into a ditch and burst into flames. Local rescuers were able to extricate the crew before the fire engulfed the cockpit. According to the pilots, the thrust reversers failed to operate when engaged.
.....
AIRCRAFT INFORMATION
The Learjet LJ-60, S/N 60-035, N1DC, was manufactured in 1994. FAA records show the airplane was registered to Ark-Air Inc., on June 12, 1997. The maintenance records revealed the airplane was on a manufacturer's inspection program and was last inspected on August 8, 2000. The airplane had accumulated a total time of 2,088 hours at the time of the accident, including 241 hours since its last inspection.
...
WRECKAGE EXAMINATION
Heavy black skid marks were noted beginning at the first taxiway turnoff about 1500 feet down the 5,010 foot runway. Two fragmented deer carcasses were found several hundred feet after impact. The skid marks continued for about 2,500 feet and departed the right side of the runway near the Instrument Landing System shack at the end of the runway and proceeded an additional 500 feet over grass and dirt. The airplane was found resting on its left side down an embankment. The cockpit section of the fuselage was crushed upward into the crew seats. The fuselage aft of the cockpit was consumed by the post crash-fire. Examination of the landing gear found all three gear collapsed and deer fur was found lodged in the squat switch on the left main landing gear. The right and left main tires had areas of rubber that were worn completely through. The flaps were found extended, and both thrust reverser’s were found in the stowed position. Examination of the cockpit found the throttles in idle, and the thrust reverser levers in the stowed position.
...
ADDITIONAL INFORMATION
With an estimated empty weight of 15,800 pounds and estimated fuel of 1,100 pounds, it was calculated that the airplane traveled 1500 feet down the runway after touchdown in 4.2 seconds before striking the deer, the performance group at Learjet using the weather reported at Troy, Alabama (variable winds and temperature at 14 degrees Celsius) the airplane landed with a ground speed of 124 knots. At 124 knots and maximum braking applied, the airplane should have come to a complete stop in about 850 feet.

A sound spectrum study was conducted using the Cockpit Voice Recorder as the source of the sound. The study was conducted by the National Transportation Safety Board's Vehicle Recorders Division. The study revealed that the engines fan speed increased from 8727.5 (82.3 percent) rpm to 9590 (90.4 percent) rpm between 11 seconds after touchdown and 18.2 seconds after touchdown. This increase in fan speed does not achieve the calculated takeoff N1, however, this engine speed is higher than achievable on a reverse thrust schedule. According to Pratt and Whitney of Canada, N1 is governed during reverse operations. The governing limit varies, and is based on ambient conditions and the airspeed. At 100 knots or greater, the maximum governing limit for N1 should be about 85.2 percent (according to Bombardier Aerospace) instead of the 90 percent found on the engines 20.4 seconds after landing.

Normal operating procedures include deploying the thrust reversers within 4 to 6 seconds after landing. Pilots deploy thrust reversers (T/R) by raising piggyback levers located in the cockpit with the throttles. With the loss of the squat switch on the left main landing gear, the T/R relay box deenergized the deploy solenoid and the T/R's go to the stow position. The electronic engine control (EEC) commands the engine speed to go to idle. As the T/R's complete the stow cycle, the unlock switches open, signaling the T/R relay box to remove the discrete signals. The EEC's switch to the forward thrust schedule and within 2.6 seconds estimated, and if the piggybacks remain at the max reverse position the engines rpm begins to increase to near takeoff power.

The airplane was released to the owners representative USAIG 2635 Century Parkway Suite 120, Atlanta, Ga. 30345.

Engines go to idle, in order to spool up the engines you need "ground mode", but also the engines RPM or power slows down automatically as the speed does, so below 80% not to much power is left on TR

ground mode for the thrust reversers to deploy is based on BOTH squat switches. ground mode for the squat switch relay box needs only ONE switch for the ground mode.
To spool up the engine during reverse operations are there one or two switches in ground mode required?

NTSB
 

October 22/08 NTSB Press Release update

DCA08MA098 includes accident summary and new factual information.

Well I think that's pretty self explanatory...

The deceleration is SO dramatic with the TR's deployed, there would be no mistake to the crew.

Especially if the proper abort procedure is followed.

The inertia generated by the Lear 60, one of the best power-weight ratio airplanes in civilian use is often underestimated. As per the detailed preliminary report out, the abort procedure was initiated at 136kts...

136kts is about V1 at MaxGW in a lear 60... This is the worst case scenario abort possible and I really feel for the people who lost their lives in this accident.

two years ago we lost both sets of Main left gear tires on a 7000ft runway but in a lear 35 close to V1, we were about 5kts below V1 but I always call V1 around that time anyways, I was the PNF and the PF hesitated for about a second (which felt like a lifetime) before taking it into the air... I called out "continue"... we dumped fuel and landed in HOU using the working parachute to stop us safely... I never asked him if he was building up a little bit of extra speed or calculating wethere we could stop (but those houses looked mighty close!)

I often wonder what if the Pilot Flying would have initiated the abort... would i still be here? to all of us operating this beast (the 60) on a daily basis this should serve as a wake up call not to take any takeoff roll for granted.

After reading the report it's real easy to come away thinking they simply screwed up a simple V1 cut. But....TRs and anti skid work predicated on squat switches in working condition. At night, 136 kts, half on the ground, half off maybe...power back, brakes on...blowtires, screwed up gear..squat switches not working...TRs don't work, and anti skid is doing funny things as the transducer on that side is probably messed up. I had the my Anti skid defaut to no brakes because of a bad wheel transducer...required air brakes...don't know on the Lear 60, but even at 136 kts and 3000 ft...6000 ft is a long way to go to just slow down..they crashed 2000 ft BEYOND the end of the runway the report said...why so fast...I don't know...

I confirmed that 136 V1 and 148 VR...that's smokin....at those speeds I wonder why they didn't pull it off...

I am SLF.

The entertainment website TMZ.com is reporting that one of the passengers and one of the relatives have lodged papers to sue Bombardier, Clay Lacy Aviation and Goodyear.
Travis Barker Sues Plane Co. - TMZ.com

(For a tabloid level website to mention 'squat switches' there may possibly be something to this 'newspiece'.)

Update there:

Probably the regular US law firm attempt to cut a deal, naturally ONLY for the good cause etc... :ooh: :yuk: :yuk:

"Not Airworthy" do they know something we don´t? :=

Anyone have an idea why they would use Flaps 8 for departure? And abort procedures for between V1 and V2?!

CD List Of Contents

Maybe flaps 8 are the normal take of setting for the 60?

it does seem unusual however that the capt briefed (and carried out) an abort AFTER V1!

Think the stats say something like its ten times more likely to have a tyre failure than engine failure on T.O.

NTSB determines cause -

NTSB Press Release from April 6/2010.


NTSB determined today - N999LJ - crash was because of operator's inadequate maintenance of the airplane's tires and the decision by the Captain to attempt a high-speed rejected takeoff, which went against operating procedures and training.

Further info from The Kathryn Report

http://www.thekathrynreport.com/2010/04/poor-maintenance-started-accident-chain.html

Sounds like when the captain tried to abort the takeoff she attempted to use thrust reversers, but instead (because of a Lear design flaw) kept the thrust going. This isn't the first time that this has happened either. Sounds to me like Lear should be doing something about this issue. It's at least as bad as the Toyota accelerator/brake issues.

What I read and heard about this accident is that the Captain took the wrong step, even the F/O called tower with enough time remmaining to advise that they were running out of the runway. In this case was a major **** by the captain, nothing to do with airbrakes, TR or brakes design. Most of those that fly the 60 for a living know it well, good brakes and bad brakes, engines and TR, blown tyres and so... I have the good brakes, 90knots and no control... It´s a fu...ing good aircraft and you still can fly the damm thing with no electronic gatchets!!!!