Comments On Removing/replacing Instrument Clusters

[GMAs]

Ahhh... well... I was reading thru the description of work accomplished... that was posted by 2362s... and after someone made a comment I have to agree with them... something is not right for all...

First they commented about the weight and how to weight the system... here they are right.. you pull the plug on the old guages and weight them its not the same as when he describes all the wiring and pigtails for the new system... so his 5.2 lbs may in fact be correct for that installation but, the removal of the old was never done right... as it to has wires and connectors... so the removal of 2 and adding of 5.2 is in question...

Next came the removal of the oil pressure lines... and here we have a delima.... I too prefer the mechanical guage because of two reasons... first redundency... if the electrical system goes out.. the engines keep runing but, the oil pressure goes by..by... how do you know when its hitting the bottom.. if the electrical system went some time earlier... and when it went so did the guages... and second... the mechanical gauges are more prone to respond much quicker than the electric ones... I don't think new technology has progressed that far that they are as quick as the old mechanical ones...

So in this area... I would pefer the older mechanical guages...

and under item No. 6... most of the 73 on do not have this in them... it would be nice but, not necessary... so cessna took it out... just like the fire light for the rear engine... it is nice to have but, not necessary unless you need it...

Now for the people who want it... ya it can be added to the system... but, it will require some splicing into the existing system and then going to and from the device... I did see a neat installation on one skymaster where the guy had digital readouts... and he put his shunts up on the firewall to one side of the regulator diodes... it was a good nice looking cheep installation... but, again do we need it... nope... I would think a simple volt meter along with the amp guage is all one would need to check his system....

Actually I think someone will eventually come out with a computer system monitoring device... where if things change.. it will show you on a screen... no more oil pressure, fuel flow, temp guages... it will note any changes and let you know... like the new 777 has... that way you have time to do other things ... like kill the duck for getting you into the clouds... and seeing if the old dog really does fly.. by itself... for looking like he would bite you... smile...

And the fuel quantity sending units are different on the later models.. with the pennycap system... than the early ones... I perfer the early ones because they have less trouble.. but, the pennycap when working right is pretty accurate and better... but, that is when they are working right... most I don't think doe... anymore... and the older systems keep on ... keeping on... smile...


and finally the item no 19... this does not fall under the normal socope and guidelines of the cessna 100 hr and annual inspection... it can be done concorently but, under the guidelines.. nope.. this is a remove and replace with type thing... and as such.. the reason why your putting it on a 337 form... for field approval...

Once it is installed... you are then supposed to have a section in the POH that describes its operation and function... and at each annual it WILL be inspected as part of the plane... like your instruments are currently at annual... the I especially liked the part ... that is on this paragraph is the ... new gauges require no additional.... maintaince... well here I would say that the instruments need calibration and certification every so often so they do need maintance... everything on the plane does... smile...

... and .. I would change the latter to... Any needed part numbers and/or troubleshooting references, which are a part of this field approval... will remain with the... ya ya... that is what the log book entry is for... the POH has the operation part... the maintance manual has the other stuff... so its Maintance records... not aircraft permanent records... kinda thing... note we only have two things that tell us how to operate our plane... the maintance and the opreations manuals... the latter being the Pilot operating handbook... now do you put the stuff in their... well the operation part... but, the maintance stuff is broken down into to areas... the log book and the maintance manual... the log book says what you did and when.. the maintance manual is what you are refered to... to do the maintance correctly... right!!!....

Test results are of no interest here... and the results that are supplied with/by Mitchell are PARTS... you by installing them in your plane and filling out the 337 form are RE-ENGINEERING to make his part fit where a old one was removed and YOU REPLACED IT WITH HIS..... Like GE made the light bulbs.. and now Cessna does... its similar but, it has a different part no... so its has a PMA or FAA approval number on it.. (they went and said.. hey we make the same thing... to the same specs.. but, its a LITTLE different so we are not infringing on their rights... and the FAA give it a approval no... after they test it...) same here...

And finally the last item... NO 20.... YA.. Ya.. again we keep seeing this statement by A&P's and IAs.. who are not with the program... here look lets go through it agan...

WE take a product..(Widgett)... its Type certificated... to go into our plane... (STC'd)... Ok.. it will work... or will it...

Some time ago we put a whiz bang in... and that had a STC also... it is placed right next to the new Product that we are going to put in now from Widgett.... but, did Whiz bang know we have a Widgett installed .. nope they only got their certification for a stock airplane... from the factory... so theirs will work... so will Widgett.. but, will they work togeather... nope... they interfer with each other... who is to blame.. the FAA, the manufacture, the owner... the mechanic... well no one... its a grey area that is not really covered... and so you give the Widgett to the mechanic and say... install... he does what you said.. but, how is he to know that the widgett and whiz bang don't get along... he doesn't fly the plane... and after all it did fit in.. somewhre...

So he goes out and runs the engine and says... its ready to go.. both come on and light up... and seem to function indivadually by themselves... but, is the plane airworthy... even with all systems operational... and he writes in the log book ... All systems functioned normally.... did he take the plane up and fly it... did he ask the manufacture... hey will this work with the other system installed also... nope.. he just said.. ran the engines and everything appeared to function correctly and normally... but, things are not right in mudsville...

So what we are asking.. and the FAA ... is that you do a compatabliity test... starting with asking the manufacture... will your product interfer with any of the other systems on the plane... and list them... letters are good... phone calls are nice... E mails are... not legal...

Most of the manufactures will know about problems that other systems have in their operation... will they do anything to correct the problems other than blame the other guy... well in the case of King radio.. and IIMorrow and their GPS's both seemed to know about the interfearance of the units.. King said ours it TSO'd and therefore its OK... IIMorrow said.. ours is TSO's and therefore its OK.. but, put the two of them togeather.. and they are not... the radio when transmitted would disrupt the GPS... so IIMOrrow gave you some attenuator pads to keep it from happening... but, King radio says ..you do that and you don't meet the specs that we certified to the FAA... and FCC for reception and range... nice huh.. your out flying in clouds and things are just ducky... till you hit that hill... because your on the frequency that disrupts the GPS.... yep and guess what its sill is... with other radios.. including kings own... so the location of the GPS antenna is real important... so is the ADF, DME and Transponder... all of which are on airplanes.. but, the DME will talk to the transponder and vice versa.. if install individually... and no consern about compatability is mentione... to the manufacture.. who will immediately say something like.. well if you use them two... you want the antennas about yea far away from each other... the further the better... but, the mechanic says.. Hey we can't hook the trailer on the tail of this beast.. so where do I put it... and they make the recomendation...

So what should have been said here is... installation was completed as per manufactures recomendations with existing systems on board. System was inspected tested and found to be COMPATABLE with other systems in the aircraft.... if you want to add you took it out and flew it and did a systems check, engine check and the rest.. its up to you... but, the key word here is COMPATABLE and doesn't interfer with other systems already installed at that date...on that plane... The wording " All systems functioned normally.... is another one that we don't like to see... instead it should be all systems functioned per manufacturs specifications in normal ranges... why because cessna didn't build the widgett... or whiz bang... they built the pane.. and the other MANUFACTURES built the other stuff.. so we have more than one MANUFACTURE... on this plane now... thus the MANUFACTURS' instead of manufacture.... smile...

YOu have to do this to maintain another word... that is coming into play... contenued airworthyness.... but, we won't get into that right now... my fingers are tired of typing and its lunch time.. smile... GMAs...