<HTML>This weekend I got a pretty good scare ...
The pre-flight was thorough and completely normal. I reached takeoff speed faster than usaual but I atributed that to cooler air, half tanks a light passenger. Hwoever, when I rotated the plane settled pronouncedly and I needed to fly quite a ways in ground effect to establish a positive climb angle. I then noticed that the altimeter and VSI had developed an ever increasing twitch. The VSI was ocillating between 0 and 500 feet up at a 1 second interval and the airpeed and altimeter was beginning to do the same. My experienced passenger calmly said my pitot-static system was hosed. I moved the "Alternate Static Source" lever on my panel and the airspeed, altimeter, and VSi all stuck - no worky. At any rate, I made a very fast landing without my airpeed indicator. I'm very glad my instructor had stressed attitude flying. I used the normal rpm settings and nose attitudes and came in fast and high - everything went fine though I must have touched down at 70 mph. The local yokels say water in the static system. They also pointed out that had I crashed on takeouff it probably would have been attributed to pilot error - departure stall due to poor airspeed management.
So, how often does the pitot-static system fail and why?</HTML>
Re: Good Scare
<HTML>I have had this problem twice. It's one reason I don't take off anything near 0/0. In one case, the pitot drain hole in the back was blocked and the idiot pilot (me) didn't notice. The second time was after a good rain when it was outside. After a few dry days, it seemed to work fine.
Fix for the first one was to pick the blockage out of the drain hole. Fix for the second one was...time and dry weather? Wish I had a better solution...dunno...
For the first one I had a portable GPS and a second pilot, so we cross checked everything (we were solid IFR).
Second one was at Big Bear, less scary but sounds just like what happened to you...
Of course the poor man's ASI (the stall warnimg horn) still works, right? Should get you back to the ground safely.
But WHY does it happen? Dunno...</HTML>
Re: Good Scare
<HTML>Pitot/Static systems can get water in them the same way your fuel system does. Condensation. If you are on the coast, and fly up to Mammoth at 12,500 feet that moist sea-level air in your pitot/static system is chilled and condenses water out in the lines. When you do that enough times you've got a blockage.
Many airplanes have a sump-bottle or static line drain. These should be drained periodically. If you have a heated pitot tube you should be turning it on even if you do not fly in freezing conditions.
And of course, rain can enter the system in some rare cases. It especially is easy if a driving rain keeps water pressed alongside your static port which sucks it inside by capillary action. (Like when the nurse pricks your finger and places a capillary tube in the drop of blood on your finger.)</HTML>
Re: Good Scare
<HTML>Thanks guys. Hopefully I'm not over reacting financially, but I'm planning to have the shop at our field go over the entire pitot-static system, replacing and upgrading where necessary. I going to ask them to install an effective water trap if one is not present. I'm also considering some kind of pitot and static port covering system. Looks like suspecting your ASI every takeoff is just part of the drill.</HTML>
Re: Good Scare
<HTML>I have a Garmin 295 - always on even for local -
usually set to half screen map and HSI info with dist to next and alt at top right - after further consideration I'll reset the screen to include speed at the top instead of dist to next - I can always scroll one page for the other stuff, but for now I think I'd like the speed ( maybe even VSI ) on the main screen - easily seen.
I know it's gps and has its limits ( including ground speed shown, not airspeed ) but I always question the ASI - and I think I'd like the "speed" shown for easy reference.
Thanks for the reminder of ASI - Pitot-Static sys potential problems
Re: Good Scare
<HTML>Most lightplane owner/pilots don't do this, but nonetheless this is an excersize you might find helpful and fun:
Next time you takeoff, note the rpm and start a timer when you release the brakes. (This is most accurate with a "brake-release" takeoff.) Also note the distance you use to reach flying speed. (This will require you to consistently use the same techniques.)
Notice that at most Federally funded/supported airports that runway light spacing is 200 feet. Therefore if your airplane reaches flying speed (say 60 kts) at the third set of lights (600 feet), and at 20 seconds, then you can make a mental note of that. Glance at the rpm at rotation speed and make a note of that.
Anytime in the future, if your airplane is indicating 60 knots and yet you're nowhere near the 600 foot mark (perhaps you're only at the second light),...or if only 10 seconds have elapsed,....then you know somethings changed. A lot. Maybe the engine isn't turning up? (Did you lean it for altitude takeoffs? Is the carb-heat on?)
If on the other hand, you're at some high, hot, desert strip and you are at the 5th set of lights before you see 60 kts you'll also know that situation is not unexpected.</HTML>
Re: Good Scare
<HTML>Water trap! Yeah, I have one of those too. But it didn't do enough to help.
"Looks like suspecting your ASI every takeoff is just part of the drill," This is where I'd go with this, although I wonder if systems with two static ports (one on each side) might have less of a problem. Otherwise, why bother to have two ports? (OK, if you slip a lot )
On my GPS I have the basics, Airspeed, Current Course, and Altitude. That way I can back up the altimeter too (at least a little).
"I know it's gps and has its limits" well, it's better than opening the window, licking your finger and sticking it out there to tell your airspeed Or dragging a wire behind the plane and feeling for a tug for altitude...(Fate is the Hunter).
"at 20 seconds, then you can make a mental note of that. Glance at the rpm at rotation speed and make a note of that"
There was an accident in Florida(?) where the EPIR ratio was wrong for a takeoff and the jet pilots didn't know the little pitot-like inlets were iced up. They hadn't followed the manual for icing procedures because they were Florida pilots and didn't think of "icing." So they set power for the correct EPIR, which was way below takeoff thrust. Plane crashed off the end of the runway. So yeah you can time it, good idea. If you wanna get really technical, I guess weight and headwind component could be factored into the timing too. Oh, and tire inflation pressure
But if you did it with no headwind at max gross at high density alitude with low tires, I guess you could use this as a "worst-case" time. And do it at a really short strip just to make it exciting! (JUST KIDDING).
P.S. Has anybody heard about picking up messages with a bucket towed behind a Cub? I guess you circle tight and the bucket stays on the ground and then you take off. I gotta go see this (maybe at Wayne Hanley's (SP?) place).</HTML>
Re: Good Scare
<HTML>Becoming aware of all the available information during every operation is a goal we should all seek. Learning how much time it takes to accelerate to flying speed, and over what distance, and what the flight AND engine instruments are telling us at that time, may someday save us. Don't just shove the throtte forward and wait for the airspeed indicator to rise to a flyable speed. Before you release the brakes, look at the tach to confirm takeoff power is available, look down the runway and pick that object that you know you should be airborne prior to reaching. Pick an object that you will use to signal an abort. At rotation speed, look at your instrument panel clock that you started when you released the brakes. Look at your tach to be sure you're still developing takeoff power.
The incident to which Mark referred was Air Florida flight 90 on departure from Wash. Nat'l. I had a close friend standing on the FBO ramp preflighting his airplane and who watched the entire takeoff.
The crew did not simply fail to follow icing procedures. The procedures to be followed were wrong. The crew did set EPR for the recommended takeoff setting for the conditions. The problem was that the inlet pitot for the EPR system was plugged with ice and therefore read incorrectly high. If the crew had not focused on only that one engine power guage, perhaps they might have noticed that the engine rpms were not in the takeoff range. ("at 20 seconds, then you can make a mental note of that. Glance at the rpm at rotation speed and make a note of that")
The FO actually did question the power setting but the Captain, relying on past experience, OK'd the reading, so they continued. At rotation the crew observed a stall warning (stick shaker) which operated continuously for the rest of the event, yet they failed to immediately do what they were probably taught since primary flight school, they did not immediately apply full throttle...all the way to the firewall.
But, it's easy to see what went wrong with hindsight! While things were going terribly wrong in that cockpit...while the airplane was not doing what it always had done in every flight that crew had always previously made...while that airplane was probably never intentionally stalled and recovered even in training by that crew....it is just not fair to find fault with that crew. They had received faulty training, had been provided faulty procedures, and were given a previously unheard of instrument system failure.
Their last words were:
FO: "We're going down Larry."
Capt: "I know."</HTML>
Re: Good Scare
<HTML>I hadn't thought of it, but night T/O might be even scarier. This kind of failure would be really hard to detect. Would you trust the AI or the ASI? That would be hard. And some places I've taken off and lost visual ref right away (Yosemite-Mariposa, Truckee, etc.), so the stall warning horn is about the only "dead giveaway."
Yep, that's right, it was an Air Florida crew. And I'd tell you there are some deeply ingrained reasons they didn't put throttles full forward.
One is ATC. On a go-around they'll sometimes call and restrict
the plane to some ridiculously low altitude (3000). With full
power and light loads, some of these planes climb 10,000 FPM.
So if the Capn accepts a restriction, you can't put full power or you scare the pax and do amazing throttle reductions. Unfortunately, Capn is overconfident and accepts the restriction. I'd just not respond and follow lost comms, fly the missed.
767 Capn did this a few months ago, and his FO didn't level until 3800. First time for this Capn in 30 years busting an altitude.
I'd say, who cares? He had TCAS, why restrict on some silly altitude when you got nothing but air in front of you? A good F/O butt-chewing and two ASRS reports later they probably went into the sim and practiced NOT putting in full power.
So he had to go around because the controller put an airplane on his cleared to land runway. Ignoring the call, saying unable, or saying nothing and flying the missed would be "very rude." Attracting attention to ATC Foul Ups is a tough spot to be in.
Second reason is maintenance. I guess some of these planes putting full throttle may put the engines in the boneyard after the flight. How's that look on a resume? "Applied 114% thrust, cost $14 million" OK maybe not that bad, but there's usually some maintenance, and you get a bad rep (stains the perfect record). Who wants to fly with an FO who used 101% thrust one time six years ago? Better remember that bad apple, right?
A coupla helicopter pilots (one a Vietnam vet) overtorqued an OH-58 148% one time. That bird didn't fly with that engine or tranny ever again...
And that's the hardest thing for me to teach some pilots, to say unable or do something abnormal. Engine failure, don't turn back for the runway! Engine out short final, land next to the runway if someone is on it! If ATC asks for an early turn at 400AGL on he missed, say "unable" if you think it's unsafe. "Get off on taxiway Echo" my butt. Hold where? Gimme a minute I'll look it up. Vaccuum failure and ATC's buggin' you, tune them off. Clouds over the south side of the airport, don't fly into them, just do right traffic or a super long straight in final (very rude). Act like a PIC, not like a lawyer. Save the passengers, not the legal fees
"I want to die in my sleep like my grandpa, not screaming like his passengers "</HTML>
Re: Good Scare
<HTML>All jet engines have overthrust protection designed into their fuel/air control systems. There is no reason to not firewall a throttle when an emergency indicates. The real problem is that airlines usually use reduced thrust for takeoffs to extend engine longevity and to save fuel. That becomes a habit that may interfere with proper thinking unless the pilot remains vigilant and is educated as to the real background of operational procedures. I say again, that crew was disadvantaged by improper procedures and training. It had nothing to do with a "go around". This was a takeoff from a standstill.
A mitigating factor in faulting the crew's judgement is that the extra-ordinary cold temperatures may have mis-led the captain to believe that a lesser throttle position was indicative of the increased thrust normally associated with cold temps. But that doesn't explain why, with a stall warning, that full throttle movement wasn't immediately applied,...unless you remember that such an action had never been taught or practiced in the airline's training procedures. (Large transport category aircraft are so capable with such large amounts of thrust available, that pilots are routinely not required to demonstrate an actual, well-developed stall recovery. Instead they are only occasionally taught to make a smooth, non-passenger-upsetting recovery from the first indication of a stall. Usually that as-taught manuever is done either in the sim or in a very light-weight training envirionment where only a slight increase of power is necessary to fly out of the stall indication.
You'd think that particular departure would be taught to every airline crew that has trained since, but sadly it just ain't so. Like I said...poor training.
I rec'd my 737 training several years after the Flt 90 incident and developed stall recoveries were never taught or practiced. In fact, approach to stalls were not even in the curriculum!</HTML>
Re: Good Scare
<HTML>Here's the final moments of Air Florida 90 (Call sign-Palm 90). Takeoff power is applied at 15:59:35 and the airspeed cross-check (eighty knots) doesn't occur until 34 seconds later! (This would normally occur in about 12-15 seconds.) Take a look at the times required to reach "Vee one", which usually coincides with Vr, the rotation/takeoff decision speed. Next time you ride on a 737, notice that you'll be airborne in 30-45 seconds normally. Even on a very hot/heavy day 45-50 seconds should have you airborne. On a cold day it should take much less time. In the Palm 90 accident, almost a full minute after engine spool up, they are just reaching a decision speed and aren't even airborne yet. The end of the runway is very nearly approaching.
CAM-1 is the Captain. CAM-2 is the First Officer. (The First Officer is the pilot flying on this departure. Notice the Captain never appears to take command (responsibility), and although he continues to override the FO's suspicion of the power setting, and continues to offer encouragement to continue the takeoff, despite the stall warning he never commands full-throttle or emergency power.)
15:59:16 CAM-2 Bleeds?
15:59:17 CAM-1 They're off.
15:59:18 CAM-2 Strobes, external lights.
15:59:21 CAM-2 Transponder?
15:59:24 TWR Palm 90 cleared for takeoff.
TWR No delay on departure if you will, traffic's two and a half out for the runway.
15:59:32 CAM-1 Okay, your throttles.
15:59:35 [SOUND OF ENGINE SPOOLUP]
15:59:49 CAM-1 Holler if you need the wipers.
15:59:51 CAM-1 It's spooled. Real cold, real cold.
God, look at that thing. That don't seem right, does it? Uh, that's not right.
CAM-1 Yes it is, there's eighty.
CAM-2 Naw, I don't think that's right. Ah, maybe it is.
CAM-1 Hundred and twenty.
16:00:23 CAM-2 I don't know
Vee-one. Easy, vee-two.
[SOUND OF STICKSHAKER STARTS AND CONTINUES UNTIL IMPACT]
TWR Palm 90 contact departure control.
CAM-1 Forward, forward, easy. We only want five hundred.
16:00:48 CAM-1 Come on forward....forward, just barely climb.
CAM-1 Stalling, we're falling!
16:01:00 CAM-2 Larry, we're going down, Larry....
16:01:01 CAM-1 I know it.
16:01:01 [SOUND OF IMPACT]</HTML>
Re: Good Scare
<HTML>Getting back to the original message.... The pitot static system works like gravity plumbing (remember the three things needed to be a plumber... payday is Friday, sh?? runs down-hill and don't like your fingers... :-) So, as water condenses in the system, it has to have someplace to go or you'll get blockage. Also, if blockage does form someplace, the alternate static source must be located such that it is of some usefulness.
So, the static plumbing should turn upward from the static port and head toward the instruments than head down cleaning toward the encoder. I would locate an alternate static source near the encoder.</HTML>
Re: Good Scare
<HTML>So there's a little bottle right where the static comes in on my plane. And I've noticed the alternate static is at a low point on the panel of most planes I fly. So maybe the bottle helps drain AND the alternate helps a little if you open it for each flight. I'm thinking there might be just a little water bubble and if you can get it to pop inside (get air past it) it will trickle down.
So if I installed an alternate static, I'd put it at a low point. That makes sense.
P.S. I like my fingers, and it's ok I get paid once a month, but I agree with the rest...maybe some draino or some prunes would help?</HTML>
Re: Good Scare
<HTML>your statement that "all jet engines have overthrust protection" is not accurate examples of engines which can be damaged by sustained firewalling of the power levers are the JT-15 in the Cessna Citation, CF-6-50 in the DC-10-30 and even the PT-6 in Kingairs and 1900's. Firewalling power levers in the first two will overspeed the first stage fan requiring mandatory teardown inspection before hot end parts start to melt, in the turbo props the reduction gearbox may be damaged and will require mandatory inspection due to overtorque before the turbines sustain overtemp damage. In the generation of engine controls before FADEC it is unusual to find a limiter on engine output except for the pilots hand.
An exception to this is found on the PT6-41, 42 series on Kingair 200's which has a torque limiter system to restrict operation above authorized power settings. It is puzzling why the manufacturers did not incoporate such systems more widely. With the coming of FADEC into common application in new generation aircraft and helicopters this capability is now with us.</HTML>
Re: Good Scare
<HTML>Actually, ALL the engines mentioned have overthrust protection except for the PT-6 series (which is actually not a "jet" engine in the sense that I intended. It is a turboshaft engine and even IT has overspeed protection in the form of a fuel topping governor.) The situation which was being discussed involved was an emergency need for power, and none of the engines of the generation you mentioned would be incapable of such "firewalling". I have over 4200 hours logged on PT-6's, of which 1200 hours are in King Air 200's and 2400 hours in 99/1900's and I can assure you that except for the overtorque condition that would require a gearbox inspection and a prop overhaul, that the engines would not have any problem with regard to overspeed condition. (Remember that little thing we all learned in ground school about 101.5% being OK for continuous operation? The fuel topping governor was even DESIGNED to operate at 103-104%, and that was actually ANTICIPATED by the design.)
So don't be distracted in an emergency. If you need the power, then for goodness sakes shove the power levers UP!
Your comment: "In the generation of engine controls before FADEC it is unusual to find a limiter on engine output except for the pilots hand." indicates you really haven't any experience operating such engines. The Bristol Siddely (Rolls-Royce) Viper 500 series was designed in the late 1940s'and it not only had overspeed AND overthrust protection, it also had over-TEMP protection and didn't require any pilot attention at all! The pilot could shove those levers up and ignore the guages completely, but that engine would self-govern and prevent any damage at all, ...all the while putting out 101% CONTINUOUSLY and without any damage or even any special inspections required! (Those engines are still under current production and installed on some current production fighters/ground-attack aircraft, some with afterburners. I've got about 1500 hours operating those and I can assure you they could care less whether the pilot slammed the "throttles" around or not!) All the other RR engines had such protections as well, either in the form of thrust limiters or "top-temp" or "fuel-trim" limiters.
The JT-8's, JT-12's, and all the rest of the Pratt and Whitney's had such protection, as did all the GE "CF" series and even the Airesearch/Garretts (and you don't FIND any more temperamental engines than the early 731 Garretts (which I have also flown a few hours), yet even they are capable of emergency power applications such as I suggested.)
The point of the discussion was that engines are capable of emergency power, and it's no time to be concerned with overboosting an engine when the stall warning/stick shaker is activated and you're only a few feet above the ground.</HTML>
Re: Good Scare
<HTML>I have about 4500 + hrs in a three way (737-300) and have experienced the same symptoms as the Flt 90 crew. In my case it was not a iced up CADC probe but a CADC internal failure. It was the FO's takeoff and it blew his mind to the point of me having to take the controls away from him. I reverted to the simple logic tought to me by a crusty old USAF MSgt FLight Engineer, when the computers say stupid thing revert to using your very own Mk1 Mod 1 computer (AKA Your brain) and verify the N1, TIT, and fuel flow values. If they are normal then the CADC is likely lieing like a dog so forget the EPR and fly N1, TIT and Fuel Flow. I learned that the hard way on C-130s that had TD (temperature datum) system to control fuel flow. They monitor the TIT and the throttle position to determin put or take on fuel flow, as the T56 people call it. They were notoriously problematic and we flew with them "Nulled Out" a great amount of the time. In that mode you must use gentle throttle changes and constantly monitor TIT and Fuel Flow to avoid big time overtourqe situtations. Turbine engines do not have to have all the automatic controls, but they sure do make life easier EXCEPT for when they fail or lie. A good driver must learn to recognize the problems and know how to respond to them. The thing that amazed me more than anything else follwing the Flt 90 disaster was that the FAA and airline seemed to blame the problem on crew coordination. Sure that was part of the problem, but a good captain remembers who is captain and responds accordingly. If you have to expain your actions to the Chief Pilot of the Feds then at least you are alive to do so. You can follow every FAA reg and every Airline SOP and still wind up quite dead if you don't take the time to learn the mechanics of the airplane and remember exactly what my old flight instructor, "Pappy Ellis" 1927-1984, taught me as rule #1 FIRST, FLY THE AIRPLANE, then sweat the small s#$& on the ground!</HTML>
Re: Good Scare
Just wanted to set the record straight...couldn't resist! The comment about not being able to overboost jet engines by applying firewall thrust is going to vary depending on your point of view. As a flight engineer with more than ten thousand hours with GE TF39's and JT 9D's I can assure you that firewall thrust will result in overboosting the engine, it will result in engine removal and tear down, based on time at temp. In some cases the engine may be left on the wing for a max of 50 flight hours, only after a borescope has been done, but then it must be removed. But in reality who cares? I spend a very large part of my life teaching in the flight sims at my 121 carrier and we teach firewall if ground contact is a factor in stall conditions. If is not a factor then Max power is used. The bottom line is it's better to toast some engines and save the airframe/people then not toast the engines, just to crash, loose the airframe/people and toast the engines in the post crash fire! Also, I never read about anyone bringing up the fact that the crew in the Air Florida 90(?) accident failed to turn on the engine anti-ice. I believe that was the root cause, or failing to do run-ups while waiting for take-off, required for ice clearing. Any way, what a great discussion...the GA portion about the pitot-static problem is intriguing.
Best to all,
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