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Another reason to hate the J?


Dan Wilson
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Does the J run off of cables or is it all fly by wire and electric throttles?

Reason for the question is the Boeing 777 that crashed/landed short yesterday at Heathrow.

From what the British investigators have released so far is at 600 AGL the pilot pushed up the throttles and the computer decided he didn\'t need power!!

Call me a Luddite but I like the idea of a direct connection to flight controls or engines, I have too many things that \"absolutely cannot fail\" fail on me.

(seems to me those guys were pretty lucky)

Dan

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Was the rumor true about the J model that took off from Keesler, lost an engine and the \"brain\" pulled back power on the symmetrical so to not induce excessive yaw, the plane narowely missed a building? Heard this many times but did not know if it was one of the many \"hate the J\" stories or if it was in fact true.

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I remember hot humid days trying to take off out of Kessler with a full fuel load and a capsule full of whining butt enders in the -7 birds.

Even with the Keyhole it was tight getting out and barely maintaining separation from the houses on a south departure. So I could see where the J would make it close on basically two engines.

Dan

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Automatically pulling the power on the symmetrical engine may be good for directional control, but that being the case, \"crash straight ahead\". That extra power may be what\'s keeping the bird in the air until the situation can be controlled. That\'s what 2 hard-pushing feet on the rudder pedal is for.

The only \"auto\" system that I thought was useful was the auto-father system on the old Convairs (T-29, C-131). Engine quits on take-off, it\'s auto feathered to reduce drag from a wind-milling prop.

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Dan Wilson wrote:

Does the J run off of cables or is it all fly by wire and electric throttles?

Reason for the question is the Boeing 777 that crashed/landed short yesterday at Heathrow.

From what the British investigators have released so far is at 600 AGL the pilot pushed up the throttles and the computer decided he didn\'t need power!!

Call me a Luddite but I like the idea of a direct connection to flight controls or engines, I have too many things that \"absolutely cannot fail\" fail on me.

(seems to me those guys were pretty lucky)

Dan

The 777 autothrotttle requested extra power from the engines but the engines failed to respond, the throttle were then pushed forward by the pilot in command with no response. The 777 and the J (along with many other aircraft world wide)uses data bus/electric singals to the engines unlike the old cable and pully system. The 777 incident could have implications depending on what accident investigators find, not just for the J but many aircraft which use simular technology.

And Herkeng130 if what you say did occur, it (the computer) acted as programmed and this is also i believe true for aircraft like the A340, A380 and new 747, in that if an outboard engine is lost the computer will reduce power on its opposite number to reduce yaw issues. I can not recall the figures it would reduce power to though. I\'ll try to look it up if possible today.

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This is from a older publication that i have access to but it gives you an idea of what the J does in this area.

The Automatic Thrust Control System (ATCS)limits the asymmetric thrust between the two outboard engines at slow speed in order to reduce minimum control speeds. The ATCSsenses the outboard engine thrust loss, either from an engine failure or power lever movement, and limits the horsepower on the opposite engine if airspeed is below a critical speed called the Minimum Power Restoration speed. The ATCS schedules thrust restoration at an ideal rate which requires approximately constant rudder force to be applied to maintain heading as airspeed changes. The ATCS schedules from 60% to 100% of takeoff power over a 30 knot range.

During ATCS operation, the power lever does not move, but the HDD Engine Status Display clearly indicates the horsepower-limited engine through the use of a blue wedge on the HP dial and a blue ATCS message below the HP dial.The power lever override switches on the outboard side of the number 1 and 4 power levers may be used to manually override ATCS. If the weight is off the wheels and ATCS is displayed below the HP dial, three rapid depressions of either switch within 2 seconds overrides the ATCS.

The manual also has a warning not use override ATCS unless an engine has failed, the ATCS degraded caution is displayed and climb performance is inadequate to climb an obsticle.

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SEFEGeorge wrote:

Automatically pulling the power on the symmetrical engine may be good for directional control, but that being the case, \"crash straight ahead\". That extra power may be what\'s keeping the bird in the air until the situation can be controlled. That\'s what 2 hard-pushing feet on the rudder pedal is for.

The only \"auto\" system that I thought was useful was the auto-father system on the old Convairs (T-29, C-131). Engine quits on take-off, it\'s auto feathered to reduce drag from a wind-milling prop.

All models of the P-3 and C/E-2 also had auto-feather...it was a nice feature, in over 5000 hours in P-3\'s I had three auto-feather events. One actual engine failure (tossed the turbine out the back) and the other two were auto-feather control box failures.

The input was from the Thrust Sensitive Switch that was part of the gearbox...not to be confused with he NTS bracket/plunger. It worked like the NTS system by sensing the torgue on the sun gear in the Gearbox and comparing it to the other three gearboxes.

The one of the very first auto-feathering systems was applied to the Grumman S-2 which had R1820-82B recips and it had air pressure sensors on top of the wing just aft of the engine nacelles. It was supposed to measure the airflow/prop wash off each propeller, compare it and if there was a specific (can\'t remember what it was)difference it would shutdown the respective engine and feather the prop. This theory was good...except first off who wants to lose and engine at the end of a cat shot as most recips do not just flame out as a turbine...and a little bit of thrust is better then none. Secondly, as the S-2\'s got older, they cut back on Cat shots and let them do deck run takeoffs. This caused problems because the wind whipping around the island of the carrier causes a crosswind effect and the prop wash pressure would be different and in the last 150\' of the carrier deck the R/H engine would cage and feather the prop. Wacky systems...

Best Wishes,

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The T-29 had the R2800-97w, if I remember correctly. The dash numbers had to do with what was mounted on the gearbox. The C-131 had the R2800-99w. Or was the 103w just on the C-118s? Damn hard to remember now. The auto-feather was turned on before take-off and turned-off after take-off. From what I remember (since 1975) was a loss of torque oil pressure. The 29\'s power indicator was Torque Oil Pressure. Same for the 131\'s through the B model. The C and D primary power indicator was BMEP (Brake Means Effective Power). This is from 30+ years ago so I hope memory serves me ok. Always remember syncing the props with a cup of coffee sitting on the pedestal. High lights, low lights (props at high or low stops). Ahhh, how I miss the days of those.

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The T-29B had a -97 on the left and a -99 on the right.(due to the hyd operated Alt/Gen). The C-131B had the 99W\'s and torque meters, The C/D/E had the 103W and BMEP. Boy, George (no pun intended) you are riviving some very old brain cells. I did 6 years on Convairs, prior to crosstraing to C-130\'s in 75.

Stoney

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The 97W on the T-29\'s had the standard exhaust pipes while the 99W had the ceramic covered exhaust pipes on the C-131\'s. The C-118\'s that I worked on had 52W version of the 2800 engine. As for the BMEP versus the Torgue gauges, I can only remember that the 118\'s one type and the Convairs had the other. I think the Covairs had the torgue while the 118\'s had the BMEP. It was 36 years ago for my memory

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joe.dawson wrote:

The 97W on the T-29\'s had the standard exhaust pipes while the 99W had the ceramic covered exhaust pipes on the C-131\'s. The C-118\'s that I worked on had 52W version of the 2800 engine. As for the BMEP versus the Torgue gauges, I can only remember that the 118\'s one type and the Convairs had the other. I think the Covairs had the torgue while the 118\'s had the BMEP. It was 36 years ago for my memory

Joe,

You are correct, the C-118 had BMEP gauges. I have my Recip FE certificate and studied the C-118 because the company I worked for was going to wake their two C-118\'s up and bring them in from the mini-bone yard. I also flew their KC-97 which was set-up for fire fighting.

We also had 2800 on our PB-4Y and did they sound cool with short stacks :) Sounded like a Harley at idle. [img size=640]http://herkybirds.com/images/fbfiles/images/PB4Y_pic.jpg

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I started on JC-131B\'s at WPAFB in ASD in 69-70. We flew a lot of different test beds on our birds. We carried 2 external power pods under the winds just to power the assorted experiments they mounted inside. In an emergency they could be jettisoned.

Ended up back at WP in 72. Started on C-118s as CC for a while, then up to FM for a time until they cut the FM slots. Then worked on T-29B/C/D and C-131C/D before I moved to T-29 FM. Did that until 75 when I flew the last T-29 to the boneyard. Told most of us we had to re-train, so I chose going to the Herc. Hit LRF July 75.

Been too many years to remember much about the recips but always loved the sound of a 118 at idle with those short stacks. The one thing I did hate was servicing the cabin compressors with Skydrol.

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It was common practice on the C-118\'s at Rhein Main in the 1970\'s to hook up a line from the fuel boost pump in the main wheel well & wash down the exhaust tracks on the flaps. Never had one blow up -- I guess we were lucky!

My favorite sound was an old Shakey (C-124 for the youngsters) taxiing by at a rumbling idle with the brakes just screaming.

Don R.

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Before I got om 130s, I had 5 years and 4200 hours on the 124. When blocking out the noise was aggravating. After landing it was a sound of joy, because you were headed to crew rest. The first time I heard them, was 1951 on a dark night at Harmon Newfoundlsnd. Scared the daylights out of me. The C-97 had squealing brakes also.

Jim

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