IBob

Well, Skippy, you're not short of advice and suggestions. Time now to actually troubleshoot the problem?

Thruster, I take your point, but I don't think it's that clear cut: what Skippy is reporting is intermittent apparent pressure drops. It seems to me that could be either pump or pressure sensing: if the sender is failing, it is possible that it does not respond reliably to the (lower) pressure of the mechanical pump, but does respond to the (higher) pressure of the booster. That's why I think it would help, if possible, to determine whether it is pump or sender/circuitry before shopping for a replacement.

Yes, that occurred to me too, Skippy. That's why I suggested borrowing a steam gauge if you can: identifies whether the problem is the fuel pressure or the sensing. And if it's any consolation regarding location, I see the Kavlico unit boasts 'Outstanding Shock & Vibration Performance' and an operating temperature range from -40 to 125'C (depending on seal material).

These are certainly considerations, Nev, but I don't entirely agree: our refrigeration ones were mounted into pipework on very big ammonia compressors, most of which run 24/7 until overhaul. Having said that, the 0 to 15PSI sender for the fuel is far more delicate than the oil pressure sender, by a factor of about 10. Personally, I would not be mounting it in the engine bay, for reasons not only of heat and vibration, but also because these are gauge pressure units that rely on also sensing a steady and accurate ambient pressure.

FWIW, I would say $300 is about the going rate for an economically priced transducer (sender). They come in: 2-wire, (loop powered), 3-wire, as this one is, 5v/0v/signal (output) 4 wire, power/0v power/Signal+/signal- (less used nowadays) This one has a 5V power in, and gives an output signal of 0.5v to 4.5V which is presumably 0 to 15PSI (though I note elsewhere that Dynon say you won't see anything below 0.5PSI.) So any sensor, suitable for use with petrol, with those operating parameters should be a direct swap-in. Depending on how far you want to dig, and on what adjustable parameters your Dynon offers, you could also swap in something with different parameters. For instance, the oil pressure transducer on the Rotax has an output signal of 4 to 20mA, (which is an industry standard) and it's quite possible the Dynon can be configured to accept that. All depends what Dynon setup you have. 0 to 15PSI is a good range for 912 fuel pressure unit. These senders are inclined to fail if the pressure exceeds their max rating. Typically we used to specify them as max pressure x 2, so for instance in a refrig setup where we might see 12 or 13 bar, we would fit 25bar transducers: that gave as a good degree of accuracy, with plenty of pressure safety margin and excellent reliability. One other note: some refrig enginerooms might have 20 to 30 pressure transducers over multiple compressors and the various vessels. Things may have improved now, but a few years back, of those 20 to 30 we would often get 1 or 2 that failed almost immediately. Of the rest, if they lasted a week, they gave no trouble after that.

I had a lot to do with pressure transducers over the years.....in industrial refrigeration and hot water systems, also in hydraulics etc. I note from the P255 data sheet: https://www.mouser.com/datasheet/2/657/sensata_p255_stainless_steel_pressure_transducer_d-1769810.pdf that it's principally for dry media, with Note 1 saying "For wet conductive media please contact us." It also notes that the internal seal needs to be compatible with the media. In short, I would be checking with the manufacturer that what you are looking at is compatible with petrol.

Skippy, any chance of getting your hands (temporarily) on a steam gauge? You could then identify whether you have a fuel pressure problem or a fuel pressure sensing problem.

Skippy, two bathroom extractors moved the right amount of air. They were 6", not the little 4" jobs. I think because they vented directly out through the (wooden) wall of my workshop. The owner who very kindly lent them had less luck, probably because he had them running out of his hangar through long spiral wound ducts. And as noted, I turned off the heater before loading the gun. It sounds like you built the Rolls Royce. My setup was a lot less sophisticated......but (more by luck than good judgement) it did work well here at the time.

In my opinion, some kit builds are badly let down by poor choice of colour and layout. Which is kinda sad, given the care and the hours that go into a build. It took me a long time to settle on what I wanted, and I spent hours over the final months looking at online pics of this aircraft before deciding on the layout. The online stuff is gold when it comes to seeing how a layout actually looks from different angles. Then I had trouble finding the colour: I knew I wanted blue, in the end I got a friend to help go through the housepaint colour cards at the hardware store, then I got the colour mixed. The layout is very traditional Savannah. I stuck with that as I think the white underside makes the aircraft look less heavy in the belly. And it's simple as it just follows the overlap in the skins. For the white tip of the vertical stabiliser, that looks right if it matches the angle of the forward strake. And another builder suggested that the registration looks best if applied fairly far back.......so I did that. Also it's on straight (and surprising how many aren't). What I didn't do was fiddle with colours and layouts on paper. First, you never actually see the aircraft in the side elevation often used for that. And second what may look good on paper can't be relied on to look good in real life.

I bought a car parking tent and erected it in the workshop. It was early spring, so heating was required. At one end of the tent I had two bathroom extractors venting to the outside. At the other end I cut a hole to take a 2.3Kw electric radiator...one of those cheap ones on little wheels. So with the fans on, air was drawn into the tent via the radiator fins. This gave steady gentle air movement that didn't kick up the dust. In the 'booth' I had a cheap wall thermometer. With aircraft part/s in place, I would switch on radiator and fans, then wait until the temperature stabilised at an appropriate level: as I recall, I would suit up and start mixing once I had about 23'C. The painting itself is pretty quick, I think I turned off the radiator before picking up the gun, as there would be plenty of residual heat in the radiator. This worked well for me. As mentioned by others, you need lots of light. This may not be essential for skilled painters, but I found the only way I could see what actual finish I was getting was to move my head so as to get direct lighting reflections off the surface. With just a few points of light you can't do this. I had lighting all down one side of the tent, that worked okay if I ran round the other side of the job. In a perfect world I would have had lighting down both sides. And if you look at professional high quality spray booths, the walls and ceiling are solid banks of lighting. (As an aside to that, if you get a 'dry' spot or area (too much air or gun held too far away) you can sometimes remedy it by loading up quickly with thinners and applying a light overspray of that. But you do have to be quick to spot it, before the paint hardens.......which requires that good lighting.) So, yes, lighting: you can't have too much. As a complete amateur (I once applied a coat of paint in an orange-peel finish to a Fiat Bambina, 40years ago, and that was it) I figured I would need all the help I could get. So I spent some time making supports to hold the wings tilted up towards me, as that was the easiest angle to be working the gun. And I rotisseried the fuselage with a suspension rope round the engine mount, which allowed me to paint it in four stages. Initially I had too much air at the gun, and had to clean back one complete wing underside and start again. I bought an air gauge to go on the gun, as the gun pressure is not the same as the compressor when you are spraying. Once I got that sorted out, and with careful focus on gun distance and speed, it went quite well. I did the colour last, and found it much easier to see how that was going on than with the white.

There are flow rate calculators for both types on line. I haven't run the exercise, but the corrugated pipe supplied with the Savannah is presumably sized correctly, as it has no problem providing adequate flows and cooling. I believe corrugated pipe does have a sharper 'cutoff' once laminar flow is lost due to liquid velocity. Which would make sense. Bobcharl, as I recall, with the pipe that goes up to the coolant reservoir, I had to complete the shaping of it in place, as when I preshaped it I then couldn't thread it into position.

Skippy 1. Unnecessary potential failure points. I agree that at first sight 'rubber' termination of metal hoses could seem, in principal, messy and over-complicated. I guess that should be weighed against the benefits in practise.....and whether these additional points do actually fail. In practise I feel the metal pipe does a good job of making the required shapes in the Savannah engine bay. And I'm comfortable with those terminations. 2 & 3. Spot on. As noted above, another member here just pointed out that those filters are no longer acceptable. I have thanked him.......and now you......and will sort that out.

Moneybox, I have just been advised that the filters you see there are no longer to be used. So, I'll be getting onto that. The hose is the correct size, as I recall, for the splitter and the carb spigots. I can't tell you offhand what size it is. I can tell you that I did the original flow testing via them, and it was very much more than adequate.

bobcharl, the flexible SS radiator 'hoses' work fine. My kit was despatched Dec 2014 with them ,and so far as I know they are still supplying them: if there was a problem I'm pretty sure we would have heard by now. To avoid chafing, it's not difficult to secure them with cable ties, threaded through a short 'bead of regular hose to space them from the securing point. And they have the advantage that you can work quite a tight bend into them without flattening or collapse, as regular hose does when bent tightly. So makes for a very neat compact installation. You still need regular hose and hoseclips to make the junction at the ends.

Aro, I can have no idea. What I was trying to suggest, in a broader sense, is that there might be some benefit in stressing certain parts of certain procedures.......and focusing on why. For instance, the standard overhead rejoin, as taught here, is well documented with minimum heights and positions over the airfield. But so far as I know, the reasoning behind that is not explained. Sure, most pilots will hopefully eventually figure out the why around all that........but why not tell them in the first place?

I think the ADS-B is a side issue: flying in that situation you would want your eyes mostly outside. And from what we have so far, it looks as though the helo may have transitioned fromapprox 200 to approx 300 late in the piece. I have wondered whether flight training would benefit from some deliberate focus on potential high risk collision points, explaining them to the student. For instance, some years ago I was almost taken out by someone wrongly located and a bit low while doing a standard overhead rejoin. I was taking off. So in that instance the risk was at the crossover point between traffic taking off and traffic crossing the strip. Had that risk been emphasised in training, we would all be aware of the need to cross with adequate height, and in an appropriate place. Similarly, I have learnt to be wary of crossing the flight path of potential outgoing traffic for many miles out, where they may still be in a hard climb, in our case in line with the strip due to it's orientation. And a third example: a very good look downwind on the base leg and before turning final. Twice I have seen aircraft coming straight in cross in front of traffic on late base leg, and both times in complete radio silence. Eventually (hopefully) we may work all these things out for ourselves. But why not point them out during training? And while it's easy to be smart after the event......if the standard helo briefing had included 'under no circumstances exceed the maximum height, doing so will bring you directly into the path of airport traffic'..........maybe all those folk would still be walking around today.

When something like this happens, there is always some discussion and conjecture. I would suggest that is human enough, and in most cases not because anyone is seeking 'likes'. And no-one is obliged to take part in any of that if they prefer not to. As fort the 'real experts', I don't know how it goes in the US, but certainly in this part of the world, history has shown they are not as all-seeing as one would wish. And the idea of us all sitting silent until they have spoken is a bit odd. In my view.

So, Deano, your principal concerns with the commentary are: 1. Assumptions as to who was flying what, and who was Captain at the time. 2. Assumptions about what sort of military flight it was, and for whose benefit. 3. Your personal belief that it is unlikely they were using NVG. ????

Specifically???

They've been working on this for 9 years. The fact that they can 'only' get a 1% reduction in drag seems to indicate that the thing was pretty well optimised to start with?

I guess, the way they are angled, the vanes will act to lift the tail. Though why that should induce less drag than lifting it with elevator trim, I don't know. Another possibility is that the modified airflow serves to reduce the 'downwards lift' of that rear section. Perhaps they disrupt the laminar flow, so causing that downward lift (or part of it) to stall?

Them's pretty big vanes at 4" x 16". Be interesting to see the detail of how they reduce drag, which the article says is the result of the upswept loading door/s shape.

KJ, if you watch the briefing, they are very specific about what they have so far in terms of altitudes. In fact they go through it about 3 times: for the Blackhawk at time of briefing, they only have ATC radar derived altitude. These choppers are part of a continuity of government arrangement, for moving government personnel out if the seat of government is threatened in some way. In those circumstances, they definitely wouldn't want to be transmitting their location by ADS-B or any other means. So maybe they run dark on these exercises???

Yes, I just saw their NTSB press briefing. While no doubt they have a long way to go, they sound fairly confident of the 325' figure at this point, derived from corrected ADS-B and another source that I didn't catch. For the helo, so far they have only the ATC radar readout, which they say shows 200', albeit a less granular (precise) source. This is understandably causing some press confusion, despite them going over it several times. I also watched commentary from another pilot who pointed out that in the necessary low level banked left turn for a landing on the shorter 33 strip, the airline pilots would have been tightly focused to the left then ahead............with the helo meanwhile coming from the right.

Deano, the Blancolirio summary I watched had the Helo at 200'..........then 300' just before the collision. I don't know how those numbers were derived. I guess we'll find out in due course. Or not.......( One of the reports right after the event contained the assertion that the airliner 'suffered a sudden loss of altitude passing over the river', or words to that effect. Where that came from, and whether it was just uninformed conjecture, I don't know. Either...