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Strange airspeed indicator behavior in rain


0TreeLemur

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1 hour ago, Chris from PA said:

Sounds like classic performance decreasing windshear to me. What were your ground speed indications? What was the reported wind? It sounds to me like you may have flown through a microburst.

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Chris,

That was my first thought as well.  

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10 hours ago, Jim Peace said:

Under a hood in VMC yes.....

who is to say the instructor is any good?  because he has a certificate, he is a nice guy, he tells good jokes, he is my neighbor?  If the instructor was really wanting to demonstrate safety the flight would be in VMC.  Going out in heavy rain or continuing into heavy rain during training just proves he needed to buy more pairs of shoes than he needed to show good judgment......fortunately they lived to fly another day.  Unfortunately we read too much about how it goes the other way.  

Maybe the last Mooney crash if the student had an instructor that beat it into him that a student or even a private pilot should not be up in the dark in mountains, that this is where the boogie man lives, he would still be with us. 

 Jim, I respect that you have conservative personal minimums.   I also respect that your personal opinion is that Mooneys are lawnmowers with wings. I don’t share that opinion and I suspect many others here don’t either.  It’s my opinion that these airframes very a great deal in terms of equipment and capability but all can be made into suitable IFR aircraft .While I’m sure the situation was somewhat unnerving for the OP,  it wasn’t very dangerous nor was it unique to his particular lawnmower. If he’d had an AOA indicator he have known immediately it was indicator error. As it stands, it was something neither he nor his instructor had ever seen before…but now they have and are both better pilots for it.  The airframe doesn’t care if the ASI stops working It’ll continue about its business either way. On the other hand, an inexperienced pilot that overreacts to a non-issue might create a problem. Going through this experience makes the OP less likely to be that guy. That is a very valuable outcome. Much more so in my opinion then sitting on the ground calling everyone who dares do something that you won’t, a dangerous insurance risk.  

If you’re truly going to treat your Mooney like a lawnmower with wings and stay on the ground at any hint of cold temps, weather, rain or wind it’s my personal opinion that you should consider an actual lawnmower with wings. Ultra lights and paragliders are positively inexpensive compared to owning and operating a Mooney and can be very safe if operated to fair weather, VFR Private pilot standards.

Edited by Shadrach
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12 hours ago, Jim Peace said:

For starters you can stop flying these lawnmowers with wings in the rain, especially heavy rain like the OP.  IMC in the rain, night time like the last mooney crash, threads about flying in a polar vortex....This is all reserved for multi engine turbines with a purpose to be there in the first place.  Not training.

Jim- you've been busy on MS recently calling others out on their decision making.  While I think we all benefit from expressing alternate viewpoints on this site, I think it's important to realize that we all have different levels of risk tolerance based on our level of proficiency, installed equipment, age, and IMSAFE factors.

I was at the peak of my instrument proficiency after getting my IFR and I was routinely flying in low ceilings with only a vacuum attitude indicator

Eight years of living in the desert later and my proficiency has decreased... now my IFR is for punching through marine layers during the day, and I wouldn't do it without my Stratus.

That doesn't mean others on this forum that choose to fly in LIFR are expressing poor decision making.

I'm glad we have a forum to discuss risk and learn from other's experiences.  But no single person's risk posture is a gold standard for coming to judgement about other's decisions. 

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18 minutes ago, Jim Peace said:

in a 50+ year old mooney???

Especially the shot gun panels.....

Yes it does.....

What does the age of the aircraft have to do with it? There are certainly panel configurations that are more ideal than others but either your scan is acceptable and you’re able to navigate and maintain control solely by instruments or you’re not. That being said, having better equipment, sophisticated auto pilots, TKS certainly moves the dial with regard to what’s prudent and or legal. The trouble is the “Dial” is different for different pilots.

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1 minute ago, Shadrach said:

What does the age have to do with it? There are certainly panel configurations that are more ideal than others but either your scan is acceptable and you’re able to navigate and maintain control solely by instruments or you’re not. 

LOL...okay you guys win.....

Any mooney no matter how it is equipped should be able to fly safely in any conditions...it all depends on how the pilot feels....

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8 hours ago, Jim Peace said:

LOL...okay you guys win.....

Any mooney no matter how it is equipped should be able to fly safely in any conditions...it all depends on how the pilot feels....

Now you’re just constructing strawmen. No one has said that. Furthermore, do you have some window into how all the aircraft in question are equipped?  You’ve been painting with very broad strokes. When called on it, you reframe the arguments put forth into something that wasn’t actually said and then sarcastically dismiss it.

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1 hour ago, N231BN said:
1 hour ago, kpaul said:
Chris,
That was my first thought as well.  

Sarcasm right???

No.  Heavy rains associated with a front will cause wind shear.  Even just heavy downpours cause shear conditions.  Even without rain here in NE Mississippi we have had multiple days with wind shear conditions at 2000' AGL.

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No.  Heavy rains associated with a front will cause wind shear.  Even just heavy downpours cause shear conditions.  Even without rain here in NE Mississippi we have had multiple days with wind shear conditions at 2000' AGL.
I understand that but don't over think the situation. He was in a constant descent and his airspeed went away. If he was in shear it would have taken a large pitch change to maintain 500 fpm. Pitch+power=airspeed. Also, shear associated with heavy rain is very turbulent. I think this is a case of an old dirty pitot system getting flushed in the rain.
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The information content of this thread has become so low that I am going to stop reading it.  Thanks to everyone who contributed a thoughtful response to my original question.  @jetdriven experienced the same problem and offered a possible, even likely, fix.   The pitot tube is just plumbing, so there is nothing pressure sensitive in it and blowing it out with compressed air with the rest of the instrumentation disconnected should not create any problem.  Of course after breaking open the pitot-static system it will need tested.  I know someone who will do that.

signing off.

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5 hours ago, Chris from PA said:

Sounds like classic performance decreasing windshear to me. What were your ground speed indications? What was the reported wind? It sounds to me like you may have flown through a microburst.

Sent from my SM-T350 using Tapatalk
 

Airspeed is a component of performance it is far from the sole indicator. With all other parameters remaining constant, a shear seems an unlikely explanation.

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6 hours ago, Chris from PA said:

Sounds like classic performance decreasing windshear to me. What were your ground speed indications? What was the reported wind? It sounds to me like you may have flown through a microburst.
 

 

5 hours ago, kpaul said:

Chris,

That was my first thought as well.  

This possibility did make me think for a second - but per the OP, nothing else changed when the airspeed went down. Seems like he would have needed a big increase in pitch and/or power to maintain the same descent rate if it were a downdraft.  Also one might expect a big increase in performance initially at the outer edge of a microburst before it drops off precipitously? Lastly he describes big twitches of the ASI needle  - these would certainly be felt hard in the seat of the pants.  It seems important to know the difference quickly when faced with this situation, so it's a good discussion point.  

It makes me think it's a good idea also to keep ground speed and GPS altitude numbers always in front your eyes for immediate reality check when in IMC in case a pitot/static problem comes up. In the age of GPS/Ipad/stratus etc, there's probably no excuse not to have this info at ones' fingertips.  

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2 hours ago, Fred₂O said:

The information content of this thread has become so low that I am going to stop reading it.  Thanks to everyone who contributed a thoughtful response to my original question.  @jetdriven experienced the same problem and offered a possible, even likely, fix.   The pitot tube is just plumbing, so there is nothing pressure sensitive in it and blowing it out with compressed air with the rest of the instrumentation disconnected should not create any problem.  Of course after breaking open the pitot-static system it will need tested.  I know someone who will do that.

signing off.

the connector from the metal pitot tube to the nylaflow tubing is just inside the wing behind the pitot tube.  Upon reconnection, instrument shops roll up a piece of surgical tubing until it reads 100+ MPH, then clip it and wait a few minutes. There is a spec for the max IAS loss.  Some apply pressurrized air to the pitot tube and destroy the 1000$ airspeed safety switch. Have that conversation before it happens. . Best of luck, report findings.

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4 hours ago, DXB said:

It makes me think it's a good idea also to keep ground speed

Yes, ground speed is a great tool if:  you are flying a stabilized approach at a set airspeed and have done some quick math between the head/tailwind component and IAS.  We have a chart to help with calculating reference ground speed.  It takes into account planned REF speed with TAS and DA then gives +- guidance for winds.  It comes in handy with reported wind shear conditions or ivo potential WS.

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