Calling All Bravo Owners

[carqwik]

FWIW, Bob Kromer (who was with Mooney a while ago...a guy who would know things of importance although I forget his title) suggested that for getting long term use out of the -AF1B, it was best to cruise at no more than 30/2400 (78%) and below 1650 on the TIT.  He told me that there was a belief "out there" that the Lycoming in the Bravo was a highly derated TIO-540, the same engine which produced 350hp in the Malibu Mirage...so running it at cruise settings of 88% power (34"/2400) in the Bravo wouldn't hurt the engine since it wasn't making anything close to the 350hp it was "potentially capable" of doing.  This is not the case at all and has no relevance. As he told me, the ideal setting for max cruise is at 30/2400 running about 100 ROP...which usually came out to be around 1600-1610 or so.  Even though the POH lists 88% power as max cruise, he said to ignore that if I wanted to make TBO without a problem.

 

[donkaye]

I replaced my first engine at 2295 hours running it as discussed above.

[johnggreen]

Carquik, Donkaye,

I want my fellow Bravo owners, you included, to understand that of all the engines I have owned and flown behind, I understand the management of the Bravo's AF1B the least.  There are lots of owners like Don who have run these engines "hard" with great success and others who have had early failures with much lower power settings.

I DON'T KNOW.

At the risk of saying that I know anything, I will give a few ideas that I think may have some merit.

I took the online Advanced Pilot Seminar and with other readings believe that I have a much better understanding of what does and does not affect the engine longevity.There are three factors that primarily affect engine life.  I'll save the #1 for last.  The other two are heat and internal cylinder pressures. Heat is primarily CHT, not EGT.  EGT is almost irrelevant it would seem if it is not creating high CHT's.  EGT's are also largely a product of where one places the probes so their temps from one engine to another don't necessarily correlate.  My Bravo is very well baffled.  Regardless of power setting or altitude, I almost never see 350 degrees on any cylinder.

As for internal pressures?  Well, there is really no way to know so if you say that you lower internal pressure by being either well ROP or LOP, my question is "lower than what".  If they are lower than a reasonable pressure, what difference does it really make.

The info learned from Advanced Pilot Seminars pretty much dispells decades of support of ROP by engine manufacturers.  The reasons that APS gives for the ROP position by the manufacturer's makes sense.  The most significant reason to me it that it is simply not that easy to do correctly.  What I do think I understand is that we should avoid the "red box".  Still, if the red box represents the settings where CHT's and cylinder head pressures are the greatest, does that always mean that "the greatest" is harmful?

The most helpful info that I gleaned from the APS is that, short of high CHT's, valves fail primarily for one reason; improper installation by the manufacturer or the installer.

I don't know exactly what message I intend to convey from this except that I think the Bravo engine is pretty much bullet proof if you keep CHT's at reasonable levels and don't overheat the turbo with TIT's.  I would hazard a guess, an amateurish projection, that most Bravo engine failures are a product of high CHT's from improper baffling or burning up the turbo or improper overhauls/manufacture.

One of my son's is very interested in the field of "behavioral finance".  We won't go there, but he constantly warns me that the most dangerous attitude is what we think we know that is in fact wrong.

So, this little treatise of mine is really for one thing; your opinions, inputs and observations.  It would be interesting to hear from pilot's who have actually experienced early engine failures on Bravo's or required top overhauls well before TBO.

OK, let's hear what you have to say.

Jgreen 

[donkaye]

I ran my first engine to 2295 hours---without an engine monitor.  Leaning was done with TIT(1625 max) with correlation with Fuel Flow.  I looked at the CHT gauge, but it never went above 350° and, of course, was attached to what was thought to be the hottest cylinder.

The first thing I did after taking the APS course in Woodland (I also took the online course afterwards, too) was have a JPI installed.  Then on return from Oshkosh that year I stopped in ADA and had the Gamis installed.  With that installation it was clear that the CHT gauge was meaningless.  I am now able to monitor the cylinder operation in detail and that has led to some changes in operation, usually in the summertime.  During some times at the higher altitudes where the air is less dense and warmer than standard, some CHTs may exceed the NO NO 400°F.  Above that temperature metal fatigue greatly increases.  So I take the action of trailing open the cowl flaps.  This costs about 3 knots but immediately brings the errant cylinder down to 390°.  All others are generally running between 340 on the low to 385 on the next to highest cylinder.  This is running the engine at bewteen 75 and 78% power, not excessively high power settings.

Maybe I'll eat my words (my total cost including labor for engine replacement including hoses checking the engine mount, alternator overhaul, etc for a reman in 2004 was $65,000), but in my opinion far too much energy is spent on worrying about how to operate the engine and not enough on how to fly the airplane.

[thinwing]

the factory cht guage (moritz analog/digital)is reading off cyl #5 if memory serves me...it is according to the jpi..the coldest running cyl...if I didnt have the monitor on all the other cylinders ,I would never know how close I was getting to 400f on a hot summer climbout.Summertime temps in the valley where I base are frequently over 100 in the pm,and I am using full rich full open cowl flaps for climbout controlling temps mostly by pitch attitude and thus airspeed .Climbouts at 600ft per min at 130 indicated are more the rule or me.I can just imagine what high temps coupled with high humidity do to chts in Mississippi...John is your Bravo equipped with an engine analyser?

[johnggreen]

Thinwing,

I bought my Bravo from Premier with 400 hours on the Hobbs.  As part of the purchase prep, I had an engine heater, GAMI's and EI engine monitor installed.  The factory CHT on my airplane is coming off #3.  Within the first few months of my purchase, I was hit with the crankshaft AD.  When the engine was reinstalled, Premier redid all the baffling for which I account my low CHT's.

An interesting note is that my Moritz guage shows over 30-40 degrees higher than my EI on #3 CHT.  They start out the same at ambient temps and spread as the engine warms.  I've had it checked several times, but nobody can figure it out.  The CHT's shown on the EI are all similar though #3 is always higher on both CHT and EGT. 

Jgreen

 

[thinwing]

That is strange..the cylinder with the double probe is the reason ..the cylinder has only 1 probe hole,so when the installers get to it they are forced to use two different style probes...a bayonet probe holding a washer style probe to the same cylinder....depending on how connections were done...the washer style reads 30 -50 degrees cooler than the bayonet style.In my aircraft..they connected 6 bayonet probes ,all cylinders to the jpi,and the single washer style went to the moritz...hence,...my low reading..yours might be reversed..k

[johnggreen]

Thinwing,

Frankly, it has been so long since we looked into the issue (and not finding the cause forgot about it) that I don't remember the details.  At my next oil change, I'll figure out the exact probe types and position.

On another note, I see that you have put in the G500.  I would like your likes/dislikes and anything you might suggest for such an installation.

I have been toying with the idea of going to a larger airplane, but frankly, I really like the Bravo.  Should I decide to keep it, I'm going to make some changes.  Here is what I have and what I think I want.  I would appreciate your comments.

Have:

2-430's, WAAS

MX-20

KFC-225 with WSI weather

Garmin TXP with traffic (half ass traffic) but will be improving or so we are promised.

KI-256 AI and King HSI.

The MX-20 is no longer supported so that is an impetus to upgrade.  I have an electric standby AI so the only thing that is vacuum is my KI-256 AI.

I figure the easiest way to upgrade the MX-20 is a GTN-750 which will also give me a 430 for trade or sale.  I can put an aspen setup of PFD/MFD which gives redundancy and eliminates my KI-256 and the need for vacuum.  I'm not debating the Aspen/Garmin PFD, which is better, but the Aspen gives me redundancy easier and is much easieer to install.  I would then have roll steering.  Then, while I'm spending money I would like to go to the new Avidyne digital AP controller which will upgrade my AP to today's technology.

Or, I could go buy an new Corvalis 400 if I can find the money!!  In which case, this economy and real estate had better see a big upturn.

So, Thinwing, what do you think from your experience?

JG

 

[thinwing]

well john at the time I did the g500 install...the aspen didnt fully support the roll steering built into the kfc225. its inyour airplane also ,its just Mooney didnt wire it to use it.So you already have a first generation but fully digital autopilot.You are correct,to doit right I had to totally replace the pilots side panel...believe it or not ,I got the Mooney factory back when they had a bunch of people standing arround ,wip it out in 2 weeks..including tryin panel,paint and lettering...now it would be a big deal...probably go with the aspen as you say...I do like the bigger screen however.All this occured at the same time I upgraded both garmins to waas..so now its mostly coupled lpv precision approaches ...I have never felt more on top of things flying single pilot ifr.I had a 696 so it was installed in a panel dock on copilots panel...my gf uses this with chartview to monitor approaches...you will come out 10lbs lighter especially after pulling the 24 lb hsi and of course dont have to worry about an expensive overhaul on the ki256 gyro...I am adding the voiceflight system next month...that will eliminate the lack of victor airways and knob twirling of the 430/530s..though Ive flown with them lomg enough to be able to do complicated reroutes with out panicking...I think I posted pics in my gallery a couple years back...check it out for ideas...regards kpc