Works slick. I already found a few improvements I can make.
One, it will have fewer bolt holes and bolts.

The first pic is looking at it from the point of view of the engine.
The second pic shows the side connected to the bends with silicon hose.
Paul Lamar

What's the failure mode for a broken throttle cable linkage?  I assume
it fails-open somehow.

Mark
--
  mark supinski
  marksupinski@fastmail.fm

Stuck at whatever it was set to last. There is a bit of friction in the slide.

Kind of hard to fail a straight, push pull 1/4 inch steel rod that goes straight
through the firewall with a knob or T handle on the end :) The only other
part is a aircraft AN clevis on the other end of the rod where is fastens
to the slide.

Paul Lamar

Mark wrote:

On many (most) aircraft you won't get this straight shot.

Fail wide open is the standard fail safe mode required of certified A/C. It would be foolish to deviate from this practice. Put a spring on it.

In Europe the requirement is in Certification Standards 23.1143 (G)
http://www.easa.eu.int/doc/Agency_Mesures/Certification_Spec/decision_ED_2003_14_RM.pdf

(g) For reciprocating single-engine

aeroplanes, each power or thrust control must be

designed so that if the control separates at the

engine fuel metering device, the aeroplane is

capable of continuing safe flight.

For those on the other side of the pond it is in FAR 23.1143 (G)

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/4810746BE2224D21852566870070BC62?OpenDocument

Remember, most of the requirements in the certification standards were written in blood!

Mark Wrathall

What do they mean by safe flight? Does the engine run at the same speed? Does it
go to wide open? Suppose the spring fails? Does it go to idle? If so how?

A push pull throttle cable is pretty robust and reliable. Anything can be designed. We could
add a spring. What do you what it to do?

Paul Lamar
In the EASA CS-23  there is no AMC (Acceptable Means of Compliance) given to 23.1143.

The FAA has published AC 20-16A which gives the following advisory material on page 153:
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/769b6362efd07b0386256e5f00502753/$FILE/AC23-16A.pdf

Paragraph 23.1143(g)

     ADC Cross-reference: None

          This guidance may be used for Airship Certification as applicable.

     What is the origin of this requirement?

          This regulation was introduced with Amendment 23-43 on May 10, 1993, and originated as a proposal in response to the Small Airplane Airworthiness Review conducted in 1983 and 1984. This
          proposal was forwarded by the National Transportation Safety Board as a response to a study of single-engine aircraft accidents involving separation of the throttle linkages with
          subsequent loss of propulsive power. The original wording of the proposal stated the following:

               "(f) A means must be provided to assure that if throttle linkage separation occurs in a single engine airplane, the fuel control will be automatically positioned at:

                 1. (1) The full throttle position for agricultural airplanes.

                 2. (2) An intermediate throttle position for other airplanes which will allow the pilot to maintain level flight in the cruise configuration."

          A review of the minutes of the Small Airplane Airworthiness Review Conference held in St. Louis, Missouri on October 22-26, 1984, reveals that the discussion was centered around the
          appropriate settings for different airplane classifications.

          The rule as proposed and subsequently accepted in Amendment 23-43 states the following:

               "(g) For reciprocating single-engine airplanes, each power or thrust control must be designed so that if the control separates at the engine fuel metering device, the airplane is
               capable of continued safe flight and landing."

          The generally accepted definition of "engine fuel metering device" is a device that controls the amount of fuel flow (fuel control in the original proposal) to the engine based on throttle
          position. The throttle refers to the device the pilot uses to set the desired engine power level.

          The intent of the rule is to keep the engine supplied with a sufficient amount of fuel to allow continued safe flight and landing in the event of a control system failure that prevents the
          pilot from setting the appropriate power level (i.e., fuel flow rate).

     Can a design that maintains positive retention of the linkage be used to show compliance with § 23.1143(g)?

          A number of Equivalent Level of Safety (ELOS) findings have been issued that have allowed linkage designs incorporating positive retention means when complying with § 23.1143(g). These
          ELOS findings have required a higher level of attachment reliability, establishment of mandatory inspection intervals, inspection procedures, and replacement criteria for the attachments.

The FAA publishes these ELOS cases (these were case by case deviations from standard practise, with a pretty heavy burden of proof).

Mark Wrathall

 
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