Terry Bowden still in busness ? or has the rain closed him down ?

[Bravo 6]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

FYI

Just a short note, I got a hold of Terry. He is still around. He is very busy with work and a wedding in the works (not his ). He said he would try to check the message board when he can.

[PA1195]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

Surely there's some latitude of acceptable performance when engines are certified. I've seen Internet talk referencing +10, -0% at that stage for normally aspirated powerplants, but that may just be forum BS (haven't researched FAA's Part 33). Once released to an aircraft manufacturer I assume it's up to that entity to implement intake, exhaust, and prop choices that ultimately affect power output for the better or worse.

I believe converting a C-85 to one of the two STC'd O-200 parts mods increases power, but perhaps it remains within the allowable tolerances for output. My Aircraft Specialties C-85 Stroker feels stronger and duplicates the performance I saw earlier with a C-90...mid-90's hp within the +10% at a rated rpm of 2575? Increasing displacement from 188 to 201 cubes and compression from 6.3 to 7.0:1 has to do something for increasing the available horses. Then there's the cam, C-150 exhaust, Donaldson air filter and so forth.

For an O-200 installation why not do what Charly Center at Crosswinds STOL did with their O-360 upgrades in Pipers...limit the power and fuel flow via specified model propeller, diameter, and pitch?

Gary

[astjp2]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

You can field approve up to a 10% change, over that is engineering/stc. per 8900-whatever it is now

[PA1195]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

You can field approve up to a 10% change, over that is engineering/stc. per 8900-whatever it is now

Thanks Tim for the info. I figured you would know. Besides TCDS data how else can an installer confirm power output? Are dyno results acceptable documentation? It would seem that with choices of engine age, tachometer accuracy, exhaust, intake, prop, and mag timing the actual power could be all over the acceptable range.

I probably will have my engine/prop balanced at some point. I've done that on a few other planes and it can make a difference in smoothness. It's ok now but I'd still like to know the IPS data in case it changes over time.

Gary

[barnstmr]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

Hello Everyone...
Yes, Greg contacted me today and told me I need to get on the forum. It has been a while since I logged on here. I apologize that some of you have been frustrated trying to contact me. I am 100% to blame for lack of response. I hate making excuses but have honestly found myself with so many irons in the fire that my email, phone, text and every other mode of communications have been a raging fire out of control for the past couple of months. I have several projects that all got held up during our Texas monsoon season, so I am way behind. It would never be my intention to leave any of you guys hanging or without support. But unfortunately, my response to basic phone calls and emails has slowed to a snail's pace lately. I think I am finally about to get back into productivity again after my son's wedding this coming weekend. We are leaving in the morning for that and will be gone until Monday. So after this, I should have no more distractions. We finally have a new Windows 8 computer in the office now and have one printer up as of yesterday. Our 12-yr-old computer finally gave up and so it is way past time for the new one. My wife and I share this computer for my side business and her full-time embroidery business... and guess who is the IT guy. Anyway.... enough of my excuses.

I am now reading my post and find that I am starting to sound like Forrest. Bottom line is, I have been lacking in my efforts to support the faithful Taylorcraft tribe and I promise to get back to business in a better way as soon as possible.

I did talk with Bernard during my lunch today and I think we are going to be able to get his issues moving.

I want to add one quick note in response to something I read here on this thread about the 10% statement in FAA Order 8900.1. That is a longstanding FAA policy that was adopted into the order a few years ago. I have applied this many times over the past 20 years. I've also sat in on numerous discussions with FAA talking about the intent of this policy. It primarily has to do with structural certification, but there are other considerations that this policy touches, like powerplant cooling, fuel flow, fuel capacity, aircraft performance, stability, spins and more (if improperly applied). I want to advise anyone interested in doing this to proceed with caution. Some people push the intent of this statement and mis-apply it by going 10% beyond the horsepower of an STC approved configuration. This is a mis-application of this statement in the Order and goes beyond its intent. Until this statement was added to the Order, all FAA engineers and DERs were held strictly to 10% over the TC certified configuration. Adding the statement into the order was never meant to allow 10% beyond STC certified horsepower without FAA or DER involvement.

If you can imagine on this subject, as you continue to increase horsepower beyond the original TC approved configuration without addressing certain items, you will eventually bust out of the original safety margins that were in the original TC approved design. I think it's easy to understand this about the structure. And fuel flow is another example (eventually, horsepower can increase to a point that the original fuel lines would restrict fuel flow... but there are potentially several other considerations that would take the airplane out of compliance with the regulations and possibly erase any margins for safety.

It is important to realize what is at stake in pushing this policy. While folks have been mis-applying it without having a problem, you might have a hard time explaining that to an insurance adjuster or lawyer if you get into a sticky situation. These things are totally at the discretion of the airplane owner and so each has to decide for themselves where the line is and how close to walk to it.

[barnstmr]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

Besides TCDS data how else can an installer confirm power output? Are dyno results acceptable documentation? Gary

Gary, et.al.
Yes dyno results are a good and acceptable means to measure BRAKE horsepower. (i.e. actual output) But keep in mind that the FAA is concerned about RATED horsepower. If you will go to the engine operators manual (put out by Continental in this case), you will find that their engines have a horsepower RATING (established by MODEL). It means that they have proven through tests that when you build the engine as noted in their overhaul manual, it will meet a certain horsepower with a tolerance of (+) plus or (-) minus some percentage. This is usually +3% and -2% or thereabouts. There are power charts in the Continental Operators manual for all of their engine models from the A40 all the way up through the TSIO-550 modern engines. When you measure BRAKE horsepower, you are determining the power output of the specific engine to see where it falls in the tolerance range of the FAA approved power RATING. Also keep in mind that if an engine puts out more than its upper tolerance on its approved RATING, it is not considered legal (without some additional certification work).

From the FAA certification standpoint, the certified installations of engines into airplanes are based on RATED horsepower..... NOT BRAKE horsepower. As you might imagine, you can make small minute changes in the parts in an engine to eek out more hp here and more hp there. For example, the term "blueprinter" engine overhaulers became a popular moniker back in the 1970s and 1980s. These aircraft piston engine overhaul companies borrowed the concepts from the old hot-rodders and learned how to polish ports, flow match cylinders and intakes, tweak fuel injectors, and other things to make their overhauled engines put out more brake horsepower in a test cell than the average stock factory engine built with the same parts. Some of these repair stations created their own standards for these things on paper with tolerances all on the (+) plus side of the engine rating, but within the approved tolerance. In doing so, they held their engines to a higher standard than the factory and were able to guarantee certain performance. This is all fine and dandy as long as the changes are done within the overhaul manual table of limits and you are not truly modifying parts. At that point, it becomes a change to the power rating of the engine and an STC is required for the engine..... and then possibly it might require an STC to consider the higher hp in the airframe too.

[Robert Lees]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

I've moved a few posts regarding Dynamic balancing to a new thread because it is worthy of a subject on it's own right.

Rob

[PA1195]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

Thank you Terry for finding the time and energy to inform and educate. It's refreshing after reading some aircraft forums where speculation and lack of verification can abound. There's room for all of that as power and speed control is what we pay for and expect, but it must be taken in context by considering the source.

Ok now a question please. Are the two STC's pertaining to modifying a C-85 compatible with your STC for the airframe and engine upgrade in a Taylorcraft?

Gary

[barnstmr]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

TOk now a question please. Are the two STC's pertaining to modifying a C-85 compatible with your STC for the airframe and engine upgrade in a Taylorcraft? Gary

Short answer.... YES.

Long answer..... On paper at least. First of all, on paper the C85 STC to install O-200 crankshaft/rods, etc was approved without any change to its power rating. Therefore the change does not require a separate STC to INSTALL the STC modified engine in the airframe. So any C85 approved airplanes can have the modified C85 engines in them without any STC paperwork.

Longer answer.... I believe the FAA got this wrong. Based on physics, you cannot take a C85 engine and change the stroke without having a significant impact on power output. The longer stroke of the O-200 crankshaft results in an increase of the displacement (cu.in) of the engine. If you call Don's dream machine and discuss they will tell you that they can measure on their dyno some significant power increases after applying this STC. [But if you ask them for an FAA approved power chart for their STC modified engines, they don't have it. They will say it is the same as the factory C85.] I think they say they routinely measure in the neighborhood of 105 hp and beyond on the dyno... when operated with the same power setting as a normal factory stock C85. That is the true BRAKE horsepower that these modified engines are producing. This is all good, except that there is no way such an engine retains its rating of 85 hp and whatever tolerance it is FAA approved with (which I think is +3%). Somehow (I think I know how) the FAA approved this and it is being done. But in my opinion, the engine should have been re-rated. What concerns me is not so much the fuel flow, because most C85 approved installations have 3/8 fuel lines and therefore a healthy margin for fuel flow. My main concern is the changed vibration characteristics and the long term durability of the parts. This is not necessarily something you'll feel by the seat of your pants. But the changed stroke of the engine will have different loads and stresses that occur with crankshaft bending etc.. and transfer to aluminum propellers, etc. Where you've got an engine that gets overhauled umpteen times, some parts could accumulate tens of thousands of hours and thus... millions and millions of stress cycles. We are already seeing crankshafts that develop cracks and not many people are thinking of the cause. Many may write it off as being operated hard by a flight school or whatever when the real cause might just be the modifications that were done.... legal or not.

Guys... they are not building many O200 crankshafts these days. Sooner or later we're going to run out. My opinion is that these modified engines will cause this to happen sooner.

[fearofpavement]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

For the T, I think an actual O-200 is a better solution than hopping up a C-85. Still not sure there's a "bolt on" STC to do this. We have over 600 hours on the O-200 on the BC-12D and it's been working out great. I don't think it adds much speed but sure allows a robust climb out. And on floats it's a huge advantage of course.

[astjp2]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

The biggest difference between the 85 case and the 90-14/o-200 is the through bolts. While the cranks may crack, what is more likely to happen with either case design is that the center crank journal wears more than the forward and aft journals because the center main bearing saddle is flexing. Don's STC was developed because they were running out of flanged 85 stroke cranks and it was a simple solution. Aircraft Accessories has the same type of STC. If you use the tapered shaft crank to keep the original stroke, where are we getting flanges from? Most crack because they are over tightened in the field. As far as the FAA getting it wrong, they only approved the data that Don's submitted, if they only said it was 85 hp, and it did not change cam profiles, its not really much of a power increase. I get a lot of this from asking questions from the people who have more experience than I do and trying to get a couple of STCs for replacement parts that have not been finished yet. Tim

[PA1195]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

Thanks again Terry for the C-85 Stroker comments. I've owned many motorcycles and can guarantee increasing displacement and compression will result in more power, as will improving volumetric efficiency via changes to the intake and exhaust, which in my case has been done on the T-Craft.

I have the Aircraft Specialties STC and it does in theory back the mag timing off (+29L, +27R), but stock C-85 timing (+30L, +28R) is within the tolerances of +-1* allowed by AS. I also have the Harer STC installed, so that's why I asked for your take on the combo. All other accessories are for a C-85 including the M/S 10-4240-1 carb, which is odd as obviously it's feeding more airflow at a given rpm...whatever. It runs well and apparently not too lean so far as I can determine.

My approach is to now treat the engine as a C-90 when it comes to operation. Static rpm is within airframe manufacturer's tolerance by configuration for the Sensenich prop which is Field Approved, and compatible with the C-90 per TCDS 1P2 Rev 15 rated at 2475 rpm, which is all the rpm limited power I need to get around. I can't see redlining the engine at the C-85's 2575 unless chased by alien craft, and it'll never do it in a max rate climb. As Tim notes the center of the crankcase supports are to be babied. Limiting max rpm may help, don't know.

Sure an O-200 would be nice but when we already have a C-85 it's hard to take the jump, sell the known history C-85, buy into an unknown O-200 (logs are sometimes just reading material), and go prop and accessory shopping. Plus then there's getting the package approved and installed all at $100/hour or more.

Gary

[astjp2]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

I want the O-200 so I can run a 74" prop for climb purposes. It also has better engine mounts, less vibration transferred to the airframe. Easier to get parts for an O-200 also. Tim

[barnstmr]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

Tim.
Just a minor correction.... Don's didn't submit any data to get their STC. They acquired the STC after it was already certified. Also... the FAA does not work the way you describe.... you don't just tell them "it' s not much of a power increase". You are required to substantiate what you are doing.

[Jim Hartley]

Re: Terry Bowden still in busness ? or has the rain closed him down ?

All other accessories are for a C-85 including the M/S 10-4240-1 carb, which is odd as obviously it's feeding more airflow at a given rpm...whatever. It runs well and apparently not too lean so far as I can see.


Hi Gary. Your statement above ,on the Marvel carb, caught my eye, as I am about to make the upgrade and retire the stromberg.

Jim