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Scary experience


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My flight school has several older Jabs online but I have only trained on one particular plane from day one.


Due to family commitments, flying now occurs on or near payday every month and sometimes every two months. It just so happened that one weekend that I intended to fly was particularly busy. There was only one plane left, same make/model that I trained on, but one i've never actually flown.


I have heard stories where the same make/model/engine will possibly fly differently to another. With a bit of disappointment, I reluctantly agreed to take her anyway as I was not prepared to wait another month to fly. Besides, I was intending to fly circuits only so no big deal or so I thought.


After an uneventful takeoff, I soon realise that the Airspeed Indicator was acting very wierd. I was on my downwind leg and it would indicate a normal 80kts one second, then jump to 120kts then back down again.


I didn't panic as I thought it could probably be the wind gusting ?!?! (at the time I thought it made sense). Anyway rather continue my circuits I decided to head out to the training area and check it out a little more. I decreased my speed to just above stall to see if it indicated a lower reading. It did. I thought to myself it's fine. But as soon as I sped up it would be erratic again.


At this point I was a little more concerned so I flew back to base and contacted my flight instructor on the radio to ask him if this particular plane had a speed calibration issues. He replied with a nonchalant "oh, yeah... just add 10kts to whatever the reading and you'll be fine "


Fine and dandy I thought, so off I went and continued with my circuits. On my base and final legs, I kept adding 10kts to what the ASI read. I looked out the window regularly and thought to myself: "plane is going too fast". Sure enough over the fence, and the plane floated and floated despite the fact that the ASI read 60kts (translates to 70kts after adding 10). Naturally I aborted the landing and went around.


At this point, I finally confirmed that my ASI is stuffed and that the 10kts crap was not going to fix the issue. In short I was in a pickle. So there I was again in the downwind leg with my ASI reading 95kts, my hands dripping with sweat, heart racing.


As a low-time pilot with only 15hrs solo experience, I then decide that I was not going to look at the ASI and instead listen to the RPM which is a good indicator anyway I thought.


I kicked myself for not taking my GPS along - at least that shows the ground speed (good enough on this windless day).


I recall during training that on the downwind my RPM should be around 2800, and just before turning base I should drop to 2100. By the time I turn final my descent should be around 500 feet/min adjusting the RPM as required to maintain this descent rate. I ignored the fact that on late final my ASI was showing only 50kts, however my hand never left the throttle to ensure full power at the first signs of a stall.


The landing was pretty smooth considering what was going on. It took about an hour to calm my nerves and realise what happened and what potentially might have happened.


A few weeks later, my instructor recalled my radio call to him and confirmed what I already knew, that the ASI was showing incorrect readings on that plane. The cause... a bug found its way in the pitot tube.


Last week I flew the same plane and surprise surprise, the pitot tube now has a cover !



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HI Moy, IMO that a/c should have been grounded, and the unservicability written up in the a/c maintenance log as soon as discovered. Something like- Air speed indicator, unserviceable -giving false airspeed indications.The notion of, "just add ten knots", doesnt cut it with me either.Thats a dangerous and a care free atitiude i reckon. Im glad it worked out OK. Im sorry for being long winded.



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Great story Moy... I agree with Dazza, just adding 10kts and she'll be right isn't good.... 10kts is a lot to be reckoned with!


I had similar experience the other day, took off in the Drifter, (hadn't flown it for more than 3 months, so was just going up for a bit to keep current). Anyway lifted off, squeezed the brakes, fuel pump off etc, and instrument checks... wait, no airspeed! So I tapped the glass, wiggled this and that, nothing.


Mmm I thought, I haven't flown this for a while, but I could still remember learning to fly it, and those times when the instructor tapes up the ASI, and or tells me to use the horizon as your speed indicator... it certainly paid off. Did a circuit and landed and found the pipe had come off the back of the pitot tube, fixed it up and away I went. (again)


My suggestion to you, (if I may). I wouldn't be so sure of using just engine rev's for gauging your speed, try and use the attitude of the bonnet to the horizon, (considering you new it, for the various speeds, "and'' settings). The engine rev's would I guess give you a pretty good indication, but the aircraft can still stall at quite a high rpm.


You can fly the aeroplane completely just by using the horizon as your speedo, try it next time and see... you'll be surprised.


BTW, great work in doing what you did, it takes a bit of will power to stay with it and fix it, I find sometimes you just won't to pull over, take a breath or two, hop out and have a look... not so easy in the air, you have to make do with what you have!



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Guest Sharp End

Sharp End's third rule of aviation... if there's an uncovered hole in an aircraft, there'll be a bug that wants to fill it.


Great job in getting her on the ground, by the way. :thumb_up:





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I would just like to add, i agree with tomo, it is good experience to cover up the airspeed indicator, and fly by revs, and atitude. If i had a A /S indicator giving false readings to the extreme, by that i mean, not fluctuating 5 kts or so, but more than that. I would cover the instrument up, by a post it note or duct tape. Some a/c- EG- the tecnams, will fly quite happily at 60 kts, by themselves, with full back trim, loosing around 500 ft per minute. Comes in handy, if you have a U/S ASI, and you want to land. Not all aircraft are the same, though.



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Hey Tomo, Just a comment about your airspeed story.


I use a quick check in the ground roll to check for things like that.


It's basically a 'airspeed alive' and a 'little back pressure' If airpseed doesnt rise as expected, abort (runway distance permitting of course)



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Hey Tomo, Just a comment about your airspeed story.I use a quick check in the ground roll to check for things like that.

It's basically a 'airspeed alive' and a 'little back pressure' If airpseed doesnt rise as expected, abort (runway distance permitting of course)

Yes, I should do that really, I do it in the Jabiru, just have gotten used to watching where I'm going in the drifter rather at the ASI. I had a pretty decent head wind that day, and me being pretty light, it's usually off the ground by the time I get the power all the way on.


Ie, Line up, power slowly on while simultaneously pushing stick forward to raise tail, and holding quite a lot of left rudder on to keep straight, by the time full power is on stick is in the center and it basically lifts off. That's when I looked down, and by the time I tapped it and what not, I was to far gone to land back safely.


But yes I should probably check it while I'm still on the ground.:thumb_up:



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Well done Moy!


It could be worthwhile to do some limited panel flights with your instructor. The aircraft flies just fine without an ASI, and you did the right thing by going back to "power and attitude = performance."


I remember doing circuits with most instruments covered during training, and it was a useful experience to have when I did end up with dodgy airspeed readings (often from water in the pitot line after rain).



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I understand the problem, as its happened to me a few times - hornet in pitot


Was working OK, went and fuelled up headed back out, No ASI. Took all of 30 min for hornet to get enough mud in there to plug it up


You really can (and have to) be able to fly without it which you did. Few more hours and regular flying build confidence when things arent right.


In training I was taught the glide approach and its amazing how repeatable it is


Turn base, power right back to idle, trim right back and Jabs just glide in. I trim fwd late finals so theres more feel in the controls


Only adjustment is getting in the right spot to turn base


As Tomo said use horizon and ground speed. GPS speed could be really dangerous, with wind and reading delay involved.



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unfortunately in Oz, airspeed indicator failures are fairly common, rain, spiders, wasps etc all love a good pitot static system to live in, so next time take an instructor with you and do an entire hour with the ASi covered, and as you did correctly before, fly Attitude + power= performance.



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I was going on a 3 hour navex for a final check before endorsement. I had only flown the J160 a few times before. On roll I noticed straight away there was no ASI. I told the CFI and asked if I should abort (heaps of runway left). He said "Nah - don't worry about it". So I did the whole navex and a landing at a new airport on the way without an ASI in an unfamiliar plane.


That was a useful exercise.


I pulled off a good landing at Tocumwal and in his typical laconic way, the CFI just said "I can live with that."


High praise indeed.


Glad you got through it OK.



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Some very 'friendly' responses to a serious story.


I'm afraid im not going to be as nice.


Firstly, as others have said, you did very well to get down ok, having not done any instrument failure training.


Let me get this straight Moy. You are a pilot?. or student?


Regardless of this, you hired this aircraft from a school?? You paid money to a commercial organisation for hire of an aircraft?


Weather its GA or RAA, that aircraft still needs to be airworthy. The ASI is a primary instrument..Its THE primary instrument. To be told after you takeoff that the ASI is U/S is bordering on criminal negligance. I'm stupified by this story.


On another note, don't get into the habbit of useing GPS for airspeed info.. Infact, don't do it. Period.


Like the guys said. Go get some panel failure training, you don't need alot for it to sink in and be affective.


I would like to say, do it somewhere else, but i'd probably get roused on.


cheers mate



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Well done in getting it down!


I agree with the others, three things:


1. The school knew there was a problem, but ignored it - that is simply unacceptable.


2. Practice with the ASI covered - my original instructor did that every lesson until I could judge it accurately from attitude.


3. Forget the GPS for airspeed.


As far as bugs in the pitot goes, we have had several instances recently (never happened before). So now all our Jabs have pitot covers.



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Guest Pioneer200

I am with merv on this one.


How could a flight school let a student pilot fly the plane with a KNOWN flaw with the ASI.


I find it unbelievable really, I can see that you can get away with it in S/L flight ,and maybe on climb out but its a really important instrument to have during the landing phase.


We all know that we want to be maybe 15 - 20 knots above stall on approach and slowly bring that speed back nearer the fence and flare.


For a low time pilot to have to figure these speeds out WITHOUT the ASI 091_help.gif.c9d9d46309e7eda87084010b3a256229.gif091_help.gif.a143ab38aa7cb6ab0af72d89d339d088.gif091_help.gif.c9d9d46309e7eda87084010b3a256229.gif



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I have about the same experience in flying as you do (hours wise).


Just a few thoughts from myself:


- I probably wouldn't have gone to the training area to check it out.


- Well done on the landing. Ignoring the ASI is a good idea. You should have trusted your gut feeling on speed etc.


My instructor actually did a circuit or two with me during training where he covered up the asi. It showed that if I trust me feeling re speed etc, I can perform better than when looking at instruments (at the time I was relying on them too much).


Well done though.







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Hmmm.. Unfortunatly, gut feelings can be dead wrong when wind is involved. The picture in the windscreen is the key. If you turn final at the right height, keep the nose down, horizen high in the windscreen, then your safe as houses.





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I wouldn't land ASAP.


What's wrong with the aircraft? Nothing really, so why land it in a hurry?


After aviating and navigating, I'd communicate my situation to those in the area. If I could I'd also let someone on the ground know of my situation so that if I need assistance they can provide it too me.



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Sorry, I thought some suggested to land "as soon as possible" rather than "as soon as practical".




edit - On the plus side Moy, you gained some experience with ASI issues and got it down safely. The very reason we log our hours, as a measurement of problems faced and dealt with.



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I had a similar experience at the same airport as MOY. I finally managed to scrape the money together to spend on getting back into flying after a 20 year break. I have GA licence.


My situation was that I needed brushing up on flying skills. Now, I've flown the usual flying school Cessnas and Pipers, but never a Jabiru. I was advised that Jabirus fly differently to C's & P's. There I was on climb out, in a circuit I was not familiar with, and the ASI needle is going back and forth across the dial like a windscreen wiper in a downpour.


Was it to be unexpected that I couldn't fly a decent circuit for love nor money? I persevered with a couple of more lessons, but the stress, and disappointment at not being able to fly as well as I used to, exacerbated my tendency to airsickness, and I unloaded my lunch into the footwell.


I decided to go to another school, whose aircraft the company I work for services. Nice new Jabs (of course meticulously maintained). I had no trouble in flying good circuits and making decent landings. The only thing that baulk me was the glass cockpit - I'm an old fashioned dial type of guy.


I agree with the comment that if anyone has aircraft for hire, either for training or touring, the aircraft must be fully airworthy. Afterall, top dollar is charged.


This harkens back to another thread in which a student asked if he should record aircraft defects on the M/R even though the student had little aeronautical experience.


Of course you should. What's the point of doing a thorough pre-flight if you adopt a "she'll be right, mate" attitude to any snags you might find.


"Fix it before you fly it" isn't a bad safety advisory. Afterall, if you crack up in an unairworthy aircraft, you'll be dead; the insurance company will pay out because of "pilot error"; and the operator will talk about the d-ckhead who wrote off the plane he had before this new one he got with the insurance money.


Old Man Emu



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I had an ASI failure on my first session of circuits, luckily the instructor was with me and showed me what to do, simple power and attitude, if the engines right (rpm), and the attitude is right, then speed should be correct. Flew an uneventful circuit and after putting her down we taxied back. Turned out the unit failed completely and is now a paperwight. Suppose it comes down to knowing your aircraft. This was in a j160



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