AVmail: February 23, 2004

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Reader mail this week about Presidential TFRs, Honda jet engine claims, funny airplane stories and more.

Presidential TFRs

Enough is enough. For the fourth time in the last five months, I have been personally affected by the Presidential TFRs. When are the NSA and Homeland Security going to realize that my Cessna 177 offers very little risk to the president? I have flown to New Smyrna Beach, Fla., for the Daytona 500 several times in the past, but can't land there (or anywhere else within a reasonable drive) this year! When I complain to the White House, I get a response from some bureaucrat from Homeland Security who obviously doesn't know a Cardinal from a Boeing!

Bob Lloyd

On Feb. 15, 2004, "Air Force One circled low over the speedway so the President could get a look -- and to give racing fans a dramatic look at a symbol of the presidency."

Since the president was not aboard, the plane could not be designated Air Force One. Therefore, wasn't the pilot violating a TFR?

Jerry Lohman

FAA Diamond Award

In reference to the "On the Fly ..." segment of your current newsletter (Feb. 16), you may be interested to know that Skyway Airlines (owned by Midwest Airlines) based in Milwaukee, Wis., has earned its seventh consecutive FAA Diamond Certificate of Excellence. Each award was earned with 100% of the eligible mechanics participating by earning an individual award.

I'm certain that there are a number of Part 121 air carriers that have tremendous training programs. I'm curious if any have had more consecutive years of 100% individual mechanic participation while earning the company Diamond Certificate of Excellence?

Steve Llewellyn
Manager, Maintenance Training
Skyway Airlines

Is SJ-30 a Submarine?

AVweb wrote (NewsWire, Feb. 19):

Sino Swearingen's SJ-30 bizjet has received pressurization certification to 31.40 psi ...

Are these people making submarines? This is more than two atmospheres of pressure.

Mike Broderick

AVweb Replies

No Mike, not an error. They put that much pressure in the hull to make sure it can handle the real loads it will encounter in flight. Here is the key part of Sino Swearingen's press release:

"Sino Swearingen Aircraft Corporation announced that it has passed the ultra critical FAA pressurization tests on the SJ30-2 aircraft fuselage to the ultimate load limits of 31.40 psi. The successful outcome of this decisive test meets the requirements for the advertised pressurization of 12 psi and 49,000 ft. altitude."

Russ Niles

Apache/T28 Incident

I was the sole observer of that entire incident (Newswire, Feb. 16). As sad as it was to see the T-28s damaged, their presence likely saved the lives of the pilot and passengers of the Apache. The Apache glanced off the side of the hanger, and would have probably rolled over had the left wing not hit the T-28s. The Apache landed on its belly, no fire, no smoke, and the occupants literally walked away, with one minor injury

It was my understanding, at the time, they could be fixed, but it wasn't going to be cheap!

Steve Candler

Honda Jet Engine

I'd like to comment on the claims reported by Honda on their new HF118 (NewsWire, Feb. 19). In that article you claimed that the HF118 will be at least 10% more efficient than anything else in that thrust class. I clicked on the link in the AVflash article to the specifications of the engine, which brought me to this page, which shows the thrust specific fuel consumption at .49 lb/hr/lb thrust at T.O. and .75 lb/hr/lb thrust in cruise.

The Williams FJ44-1A -- although slightly larger (1900 lbs thrust vs. 1650 for the Honda) -- claims identical if not better fuel consumption. Takeoff is specified at .48 lb/hr/lb thrust; and in cruise at 30,000 ft. and Mach .70, Williams claims .75 lb/hr/lb thrust. Its thrust-to-weight ratio is nearly identical. This is from an engine that was designed about 10 years ago and has been used in the highly successful Cessna CJ1 for many years.

Williams is claiming yet even better fuel specifics for their new FJ-33 engine line.

Greg Wroclawski

AVweb Replies

It was important today that our readers were made aware of the breaking news and provided with resources for further information.

For the record, what we said was: "Honda and GE say the engine is 10 percent more efficient than comparable designs." We'll look into exactly what they meant by that, but Honda has not been terrifically forthcoming. (Honda also claimed a 40-percent increase in efficiency for strapping its engines to its own airframe.)

Thanks for using AVweb. We appreciate your well-crafted note.

Glenn Pew

Funny Airplane Stories

I enjoyed the funny airplane stories (Newswire, Feb. 16). However, I think the article about the dry ice and the reaction of the airplane's toilet system to the addition of a block thereof has all the hallmarks of an urban legend, and as such is of doubtful veracity.

First off, the placement of a two-pound block of dry ice in a Coleman cooler (or any other kind of off-the-shelf cooler) would probably have drawn the notice of the airplane's crew fairly early on, particularly if the cooler was reasonably leak-free and the lid of the cooler was tightly closed or latched in any way. The sublimation of the dry ice, CO2, from its solid to its gaseous form, would have resulted in a significant (!) increase in pressure inside the cooler. Depending on how gas-tight the cooler was, the result would either be a hell of a bang as the lid was blown off, or a noticeable venting of chilled "air" from leaks in the cooler as the dry ice evanesced.

(Where I work, some of us with access to dry ice used to enliven staff meetings from time to time by putting pellets of dry ice into the little plastic bottles 35 mm film was packaged in. The CO2 would blow the top off the bottle with a gratifyingly loud "pop." A colleague created a CO2 bomb at a party once by putting a large quantity of dry ice in a 2-liter soft drink bottle, then screwing the top on and running, very fast, from the location where he'd put the bottle. Don't try that at home! There is a potential for severe injury from being hit with the bottle cap or plastic shrapnel.)

Second, it's unlikely that any adult would ever mistake a two-pound block of dry ice for a comparable quantity of water ice. It doesn't look the same, and the effusion of "smoky" plumes of cooled water vapor arising from it, plus the "fur" of frost growing on it, would alert even the most mind-numbed second officer that the substance wasn't normal water ice. Any physical contact of skin with dry ice would reinforce that impression, because dry ice -- with a temperature of about -109 F -- is so much colder than water ice.

Further, a two-pound block of dry ice, dropped into the bowl of what passes for a toilet in an airplane, would definitely not be able to pass whole and entire through the valve that separates the toilet bowl from the "holding tank" of an aircraft's toilet system. It would sit there, making vapors and causing evil whistling/humming noises from the contact with the metal sides of the bowl, until finally it evanesced away. While doing this, it just might cause the valve in the toilet bowl to freeze.

The story describes the cascading reaction of the contents of the toilet system tank with the dry ice as the result of "two pounds of solid carbon dioxide mixing quite unhappily with a tank full of acid."

Quite unhappily for the writer of this story, the fluid used in the toilet systems of aircraft does not have an acid pH; it has a neutral to slightly basic pH. The Aerospace Material Specifications (AMS) that cover the solutions used in the toilet systems of aircraft are AMS 1475, which was inactivated for new designs in March of 1994, and AMS 1476. AMS 1475 specified a formaldehyde-based solution with a pH 7.5 to 9.5. AMS 1476 does not specify either the composition of the solution or the pH limits, but there has to be interchangeability between the two specified solutions, or the AMS 1476 solution could potentially cause damage to components of the toilet systems that used AMS 1475. A quaternary amine solution seems to be the commonly-used AMS 1476 product, and this has a pH that is neutral to slightly basic -- not acidic, as mentioned in the story. CO2 will react with water to form a weak acid, H2CO3, which will react with a basic solution to neutralize it. Dry ice in a solution of sodium hydroxide can produce a nice lot of "fog," but the observed strength of any chemical reaction is going to depend on the concentration of the chemicals present. It's fairly obvious that the concentration of whatever chemicals are used in the toilet system of an aircraft is going to be, for safety reasons (as well as economy), as dilute as possible.

Finally, the volumes of foam alleged to have been produced after the reported dumping of the 2-pound block of CO2 into the toilet system again call into question the veracity of the story. AMS 1476 has a requirement that foam volume of the solutions used in the toilet systems "shall not exceed 5 milliliters when 100 milliliters of diluted product is shaken in a 200 milliliter-graduate [receptacle] for 15 seconds and allowed to stand for 60 seconds." This means an increase in volume of not more than 5 percent. Hardly enough to account for the volumes of material described as emanating from the toilet.

It makes a good story. The mental images created are certainly vivid. But I think that we'll have to consign this one to the urban legends file, or maybe the apparently defunct AVweb April Fool's edition.

For what it's worth, here is an interesting account of an actual problem encountered by a flight crew carrying a load of seafood that was cooled with CO2.

Karin Cozzolino