260B – Are CHT & EGT required instruments

[PhilH]

During a recent panel upgrade I asked if either the CHT or EGT indications were required for our 260B. We retained the existing single ALCOR gauges so didn't matter but it will when we install a future engine monitor for lean-of-peak operation. The avionics shop said both are needed but they were not very clear as to why. DOES ANYONE KNOW THE ANSWER AND REASON?

Here is what I have found:
1) In a 24 Aug 2010 post Zach Grant said: "No, you do not need a CHT or EGT as per the TCDS for the PA-24-250, or for the certification regs (CAR3) that the aircraft is certified under. EGT's were a factory option, never required, and CHT's were only required on those aircraft with cowl flaps."

2) I looked at the Type Certification Data Sheet (TCDS) 1A15 for the PA24 and found the following:
- Exhaust Gas Indicators are identified under item 607 under "Miscellaneous Equipment" but are not otherwise discussed except requiring a flight manual supplement when item 607 is installed.
- There is no reference to cylinder head temperature anywhere in the TCDS.
- Under model PA-24-260 – Required Equipment - it says "In addition to the pertinent required basic equipment specified in CAR 3, the following items of equipment must be installed." Item 607 is not identified.

3) Per Civil Air Regulations 3 (CAR 3) – 1949:
- I found no reference to exhaust gas temperature.
- Per § 3.675 Cylinder head temperature indicating system for air-cooled engines. A cylinder head temperature indicator shall be provided for each engine on airplanes equipped with cowl flaps. In the case of airplanes which do not have cowl flaps, an indicator shall be provided if compliance with the provisions of § 3.581 is demonstrated at a speed in excess of the speed of best rate of climb.
- § 3.581 simply says cooling systems shall maintain engine and fluid temperatures at or below safe levels during flight and ground operations.
- I assume Piper demonstrated adequate cooling at or below the best rate-of-climb speed and the 260B has no cowl flaps, therefore CHT is not required by CAR 3.

4) Killough POH Section 2, Limitations, page 2-3 discusses cylinder head temperature limits. Per the avionic shop since min and max values are specified in the Limitations Section, CHT should be considered a primary instrument.

5) Piper's original "Comanche 'B' Owner's Handbook" makes no reference to exhaust gas or cylinder head temperatures.

[JIMICS2452]

That is why I don't use the Killough manual as my flight manual or have a copy in my Comanche. It adds a number of requirements that are not in the original Piper documentation.

[N3322G]

Phil,

For a Twin it may be different - I know the FAA requires CHT to always be displayed for an aircraft with cowl flaps so our 11 year old JPI760 is not allowed to replace it. Newer JPI gear does have an STC to replace the CHT gauges.

[Kristin Winter]

I don't use the Killough manual for anything other than reference for the reason Jim states. However, I am not worried about it being in the aircraft as there is no 337 filed adopting it as the AFM. Doing so would very likely be a major alteration, but even if not, there would still need to be a log entry. I am betting that the vast majority of owners using the Killough manual are probably illegal as they don't have the original AFM and they have not done the paperwork to officially adopt the Killough manual.

[Charles Schefer]

Kristin - thanks for this comment. I have not filed a 337 or made a log entry regarding my use of the ICS manual. I am going to talk to my PMI at the FSDO again. When I last discussed this topic with him he actually told me I simply needed to put the one I was claiming as "the" AFM in the aircraft and claim it as such. I think I'll discuss this with him again this week. I would think a log entry would suffice over a 337 but I am happy to do either. I suppose keeping the original aboard also solves the issue as you do and given our other discussion on ice - leaves more overall flexibility

- Charles

[Kristin Winter]

Of course, I am looking at this from a lawyer's point of view. Like any alteration, there has to be some sort of declaration of which is being used. If you change he AFM, you are altering the aircraft. The TCDS calls for one AFM specifically, so I am thinking that changing from what the TCDS calls for, is a major alteration hence the 337.

[Charles Schefer]

I agree but I'm not sure I'd consider the change of AFM "major". When we move Cirrus aircraft from Part 91 to Part 135 Conformity under our AAIP, all that is required is a logbook entry counter signed by our PMI. That's an entire maintenance program change not just an AFM. I'd think a 337 would not be needed. I'll ask the FSDO. Of course I've found every FSDO and even every inspector often has a different opinion...

[Kristin Winter]

[Charles Schefer]

[Kelly W Kober]

My original panel had an EGT gauge but no CHT. When I had the panel redone there was a lot of discussion with my installer if we needed to retain the individual gauge even though I was installing EGT/CHT's for all cylinders on an EI multipoint readout. We elected to do away with the individual EGT but I remember the decision was still doubtful.

[PhilH]

THANK YOU ALL FOR YOUR RESPONSES - BUT VIRTUALLY ALL FOCUS ON THE KILLOUGH AFM AND NOT MY QUESTION ABOUT WHETHER CHT AND EGT ARE REQUIRED.
FOR SIMPLICITY PLEASE ASSUME THAT I AM USING THE ORIGINAL PIPER AFM (WHICH I HAVE) AND NOT KILLOUGH.
I PROVIDED ALL OTHER REFERENCES I COULD FIND IN MY ORIGINAL QUESTION.
THANKS IN ADVANCE FOR YOUR HELP.

[Charles Schefer]

Sorry Phil you're right we strayed off topic on the manuals debate...

Well here's my 2-cents. FAR 91.205 spells out the basic required equipment for flight (link below). There is no reference to EGT. So.... I think it would be up to the limitations section of your AFM or the equipment list section of the AFM. Limitations section is Section 2 of a modern AFM. In the ICS Killough manual it is Sect 2 but in my original PA-30 manual the limitations section is Section 1. In my original PA-30 POH/AFM I see nothing that references a Section 1 Limitations section reference to the EGT gauge or readings. In the weight and balance section there is also an equipment list (again in my original PA-30 POH). All mine indicates is what is installed - no reference to required vs not required. All this said what does your 260B POH say? If you can find no limitation requiring an EGT and since 14 CFR 91.205 does not require an EGT for flight... I guess you don't legally need to have it. Here's the reference (link below). I'll chew on this some more...

http://www.ecfr.gov/cgi-bin/text-idx?SI ... 5&rgn=div8

- Charles

[Zach Grant L1011jock]

As you cited before referencing one of my answers, no, EGT and CHT are not required instruments in a 260B. CHT is required in a 260C due to it having cowl flaps (and thus requiring CHT displayed per CAR 3). As far as using the numbers in the Killough manual as justification for requiring instrumentation, your radio shop is just wrong. The numbers published are straight from the Lycoming book, and regardless of its inclusion in any POH/AFM, they exist in the operators manual for your engine. Yes, they are limitations placed on the engine by certification, and you can look them up on the TCDS for your engine.

Just because there is a limitation, doesn't mean there is necessarily a gauge that goes with it. Just one example would be "G" limits. They are published as limitations, but a G meter is not a required instrument. Gross weight is a limitation, but there are no scales...I'm sure you get my drift.

In simple terms, the lack of anything saying you must have a piece of equipment in an aircraft means it is not required. You will not find a list of all things not required, only those things that are, and you need to draw conclusions that everything else is optional.

Zach