ADAHRS Fail

[SkippyDiesel]

You sound like a priest - ignore what doesn't suit your perception of reality, repeat the same statements ad nauseam, in the hope someone might accept your faith.

"Collective wisdom...." . as you are the main respondent, this smacks of delusions of grandeur .
"WE can't tell you any more than that" - What's with the Royal We ?? - This sort of outmoded language is used by the British Royal Family - are you a member or just aspiring to join their inbred tribe??

You seem to wish to belittle me in your repetition - "....yet you continue to argue and swap out more ADAHRS units." DYNON IS RESPONSIBLE FOR SUPPLYING MULTIPLE ADAHRS MODULES #53- my contribution has simple been to relate symptoms/faults.

"Most likely within the SV," - check out post #46

I think you may have assisted ?? me a to the limit of your understanding and your comprehension of writen English. Should you suddenly have something constructive to impart, I will respond appropriately, otherwise this is my last comment to you .

 

[SkippyDiesel]

Good news at last!

Today, I called Dynon Australia for the umpteen time (the receptionist recognises my voice immediately).

The Boss had gone to Oshkosh, so I talked with one of the LAME's - We reviewed my 6+ months problem & all Dynon & I hade tried, to effect a fix - He then relayed a recent experince he had had with an aircraft fitted with a Dynon system - After satisfactory ground test, on TO, air speed indication refused to increase past a certain point and then decrease - partially blocked pitot/static/or A of A
He suggested I disconnect pitot/static/A of A from the ADAHRS module & see what happened - EUREKA!!! ADAHRS came straight back up on the SV.
With a small 12V tyre inflator I blew out all 3 tubes - all appeared clear (no backpressure).
Reattached and system continued to work as expected.

I am very hopeful that this simple remedy is THE FIX. Time will tell. In the past the system has worked for 3-6 Hobbs hrs before failing.

 

[jakej]

JakeJ said:
Have someone else sort it out properly AFTER a genuine Dynon heated/unheated Pitot is installed. How will a Dynon pitot change the simple physics of pneumatics?
Do you now understand why I made the above statement re replacing your ’home built’ pitot/AOA tube with the tried/proven Dynon tube? I suspected that was the cause but what confused me was your statements about it ( your unit) working on the ground or for a very short time.
Your penny pinching has caused a lot of angst all round & expense. Hopefully you’ll make peace with Dynon, at least, as you caused all of this.
’Over & out’.

 

[airguy]

Why do I feel like we're being trolled here?

Don't feed the trolls.

 

[swatson999]

Don't feed the trolls.

Characteristics​

A troll usually has little or no interest in contributing to the development of the site in question and is interested in some or all of the following:

• Deliberately angering people.
• Making people act or say things that are considered obvious, causing the individual to appear stupid to others witnessing the discussion.
• Breaking the normal flow of debate/discussion.
• Disrupting the "smooth" operation of the site.
• Deliberately being annoying for the sake of being obnoxious. For instance, using abusive names to refer to all the members on the site.
• Pretending to be profoundly ignorant or stupid, gleaning some weird sense of having "won" when other users subsequently come to believe this.
• Making itself the main topic of interest or discussion.[note 1]
• Engaging in performative disruption, that they can then brag about somewhere else.

(Courtesy rationalwiki).

 

[SkippyDiesel]

JakeJ said:
Have someone else sort it out properly AFTER a genuine Dynon heated/unheated Pitot is installed. How will a Dynon pitot change the simple physics of pneumatics?
Do you now understand why I made the above statement re replacing your ’home built’ pitot/AOA tube with the tried/proven Dynon tube? I suspected that was the cause but what confused me was your statements about it ( your unit) working on the ground or for a very short time.
Your penny pinching has caused a lot of angst all round & expense. This is a plans built aircraft. The design & construction of the pitot system in in keeping with this concept. This comment is personnel, without evidence, not constructive, unfortunately part of your pattern of questionable advice??& Hopefully you’ll make peace with Dynon, As far as I am aware Dynon have no problem with me, have been prompt to try and diagnose/fix what they (& I) perceived as a computer/electrical glitch. The LAIM who finally came up with the solution(based on his recent experince) made the comment - "we should always try and think outside the box" at least, as you caused all of this. Once again you make this personnel - why on earth would I or anyone, wish to go through months of inconvenience, restricted flight hours, lost opportunities and it needs to be said, the discomfort of communication with the likes of Swatson999 & yourself, in the faint hope of assistance???
’Over & out’.

The likly source of the partial blockage is condensation, combined with my aircraft being a tail wheel.
I can do nothing about the atmospheric water vapour or its tendency to condense on/in metal surfaces/structures.
The tail down stance of the airframe, means that the pitot system is tilted up, while on the ground. It would only take a small amount of condensed water to collect in the inevitable bend (found in most if not all underwing pitot systems) causing a partial/total blockage.
The above theory explains why the problem has always occurred on the ground.
I have no intention of changing my otherwise perfectly satisfactory pitot system. Should the theory prove correct, any future ADAHRS failure indications will, in the first instance, be addressed by blowing out the pipework.

Dynon, the members of this Forum and I have benefited (gained knowledge) by this experince.

I thank those who lent a sympathetic ear and condemn the few, who have taken the opportunity to be unpleasant & ultimately unhelpful (TROLLS?) .

 

[swatson999]

The likly source of the partial blockage is condensation, combined with my aircraft being a tail wheel.
...
The tail down stance of the airframe, means that the pitot system is tilted up, while on the ground. It would only take a small amount of condensed water to collect in the inevitable bend (found in most if not all underwing pitot systems) causing a partial/total blockage.

Someone correct me if I'm wrong, but isn't *every* taildragger's pitot tilted up while on the ground?

Why haven't the thousands of other tailwheel planes with Dynon equipment suffered the same problems as our OP?

 

[airguy]

Sounds like one of these things is not like the others. I seem to recall Sesame Street doing a piece on that for 4-years olds...

 

[chriscalandro]

Because Dynon, and other properly designed pitot tubes have drain holes specifically for this reason.

 

[swatson999]

Because Dynon, and other properly designed pitot tubes have drain holes specifically for this reason.

That's true, but then again, I didn't build one that used the roll-your-own pitot tube that Van's called out in their plans, at least the earlier models. Did those plans include adding a drain hole to the bent aluminum tube? I honestly don't know the answer here.

But...I suspect they did not, which would mean the question still stands. How come all of those planes flying around with aluminum tubing pitot tubes don't report the same problems as the OP?

ETA: See attached, straight from the plans (RV-7A in this case)

 

[greentips]

Interesting morning read (while looking for something else). Early in the thread, I suspected as did others the problem was outside of the ADAHRS. Electrical seems to have been checked thoroughly, which leaves the plumbing. I fly Part 23 airplanes and on the PA28 checklists they discuss checking the pitot mast including the moisture drain for obstruction. I don't know what kind of mast, and the OP did not specify other than homemade, which in the interest of comity he could have included a picture to demonstrate his engineering prowess. Every airplane I've flown, from the smallest Cessnas to the biggest Beech has pitot/stati drains and moisture control.

It might be useful to review the US FAA's Pilot's Handbook of Aeronautical Knowledge (PHAK) Chapter 8 which describes in lovely pictures the moisture drainage solutions of the various forms of Pitot/Static systems. And a reminder to check the alternate static source (If EAB aircraft have/require them). I have had two pitot/static failures in 47 years of flying, one a mud dauber in the pitot found on preflight and an hour long ordeal cleaning the pitot tube and downstream in the field. The second a plugged static port from hidden ice.

The OP relates that his problem solution in post #66. Well and good. The failure was, as others indicated, in the plumbing design and not the measuring device (ADAHRS). OP correctly notes that his problem is due to blockages in the pitot/static system. I have concerns with the OP's conclusions though:

The likly source of the partial blockage is condensation, combined with my aircraft being a tail wheel.
I can do nothing about the atmospheric water vapour or its tendency to condense on/in metal surfaces/structures.

and

I have no intention of changing my otherwise perfectly satisfactory pitot system. Should the theory prove correct, any future ADAHRS failure indications will, in the first instance, be addressed by blowing out the pipework.

It seems to me that an in flight failure of a pitot static system is a serious problem and more than one pilot has died from this type of failure. (See NWA FLT 6231 01DEC1974 2326Z B747-200 JFK-BUF stall spin fatal).

I would not consider the OP's assertion that his Pitot Static System is perfectly satisfactory a reasonable conclusion in light of multiple instrumentation failures. Given the series of failures experienced to date which were detected by his Dynon system, I would take the next step as a former Aviation Safety Counselor to advise the OP that unless he plans to fly only on dry days VFR with no possibility of rain, and disassemble and clear his static system as a pre-flight action before every flight, he should consider redesigning his system to resolve this defect. Considering the risk, especially if there is any chance of inflight moisture or freezing temperatures above the ground, it is my opinion that this is an unsafe condition.

I disagree with the OP's contention there is nothing he can do about humidity and condensation. We have long ago learned how to solve these problems by providing drains in systems predisposed to condensate collection.

Early on OP was defensive when a poster with clearly significant knowledge recognized the problem may lay with the plumbing. It turns out the OP's problem was the plumbing.

 

[chriscalandro]

The OP has a history of not understanding basic concepts and troubleshooting / resolutions available and presented to him (ie fuel flow “mystery”)

He is seemingly combative and either unwilling or unable to perform the checks, procedures, or maintenance items presented to him either from the installation manual or this this forum.