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| Turbines typically get Vno and not a Vne. That has Mach implications for the high flyers and Mmo takes over depending on which is reached first. For the TBM 700 I fly Vno is 266 and we get there only on full power descents, not in cruise. Because of max altitude restrictions, the max Mmo is not an issue for us and not listed in the POH. I'm *guessing* the same issue goes for the IV-P? If you were able to go higher then Mmo might become an issue and be listed if you had sufficient power and it differed from the Vmo limits. It sounds like the 276 KIAS limit probably takes all those factors into account with a single safe number albeit close to what you cruise at and possibly always under the Mmo figure.
Paul Legacy, Calgary On 2012-07-13, at 1:58 PM, Bob Rickard wrote: My IV-P shows a red line on the Chelton system at 276 KIAS. The POH says the same. I have been close to there more than a few times, which means if it is meant to be TAS I have been WAY over that. I highly doubt Jeff Edwards messed that up when getting the flight certificate on my airplane. Can't be right, I can almost cruise at 270 KTAS at FL250. Definitely not a universal rule.
Bob R
Well that's interesting. FAR Part 23 (airworthiness standards for normal, utility, acrobatic and commuter airplanes) Section 1545 (airspeed indicator) says that the airspeed indicator must be marked with a red line at Vne (that would be an indicated airspeed) and that if Vne varies with altitude, there must be a way of indicating Vne to the pilot throughout the envelope. For airplanes operating at Mach numbers where compressibility matters (not Lancairs), Vmo is defined in Equivalent airspeed, which is still very close to IAS, and there has to be a way of showing the variation of Vmo/Mmo with altitude and Mach number.
I've never met a light aircraft instrument system that had a primary airspeed indicator with anything *other* than IAS, and just one redline value. The Garmin 900, and I guess other EFISs, also read TAS but not on a big pretty scale with a redline. You can set the redline on the airspeed tape conservatively so that it's below the lowest TAS for flutter at any altitude; then you give away a few knots at lower altitudes.
How many folks spend any time at redline? I've never gotten anywhere near it in my Legacy.
Charley Brown Legacy #299 130 hr
On Jul 12, 2012, at 9:26 PM, Steve Colwell wrote: Having coffee with some high time pilots this morning, the subject of Never Exceed Speed came up. Before I read the original Van’s article years ago, I thought Indicated Airspeed was the indicator… WRONG, it is True Airspeed. Does your EFIS display TAS or do you have a table for reference?? Steve Colwell Legacy
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