Letters: 01/04

WAAS Worries
I enjoyed your article on the status of GPS WAAS in the November, 2003 issue. On page 18, you used the example of the GPS 32 approach at Gaithersburg, Maryland, my home base. While this demonstrates the potential benefits of WAAS, this particular approach is totally useless to civilians.

Thats because you need to enter the FREEZE zone surrounding DCA VOR. My guess is that only when hell freezes over will civilian aircraft be able to enter that zone. The approach is not available at night.

Look at the weird wording they use to say that on the chart: No straight-in or circling at night. (What else is there?) The new GPS 14 approach also uses the FREEZE zone for the missed approach and is not available at night.Having to cobble together an ATC-assigned, non-published missed approachpoint in your high-tech GPS to avoid PFR (permanent flight restrictions) airspace, a point which may not be inthe database, which will not be in the automatic sequence logic of your GPS and which will not show a holding pattern, is not my idea of simplicity in operation that all this high-tech stuff is supposed to provide.

Im trying to get a ground swell going to get the FAA to reinstate the former RNAV 14 LNAV approach that doesnt require flight into the FREEZE zone and is available 24 hours a day.

-Herbert A. Rosenthal
Bethesda, Maryland

The FREEZE zone is otherwise known as the FRZ or flight restricted zone. It overlies the boundaries of the TFR established following the 9/11 attacks.


Vacuum Retorts
I am frustrated to have to write you regarding an article that appeared in the November, 2003 issue of your periodical. I understand that you have outside sources for some of your material and checking the veracity of the information is a daunting task. However, the bias illustrated in the article, Better Vacuum Pumps will most likely cause harm to Rapco, Inc.

Rapco was cited as a source, but yet the body of the article addresses issues relating to Rapco that are false and damaging to Rapcos reputation in the industry. Rapco has never manufactured, distributed nor endorsed the use of repair kits. Including this falsehood in the article countermands 20 years of effort to persuade end-users not to use kits.

Editorializing on the nature of our advertising smacks of bias, as was done with the use of the word sarcastic [in reference to our ad.] Id expect a critique of our advertising in Advertising Age, but not in an aircraft resource magazine.

I am sure that my sales manager, Mike Lotzer, would have supplied the voluminous data to support his contention that in certain applications, our product will last as long as he purported…in lieu of having his contention mocked in your publication. If your author doubted the claim, he could have asked for further information in the spirit of maintaining fairness.

I understand that it is the prerogative of the author to state his preference, but your readership could have benefited from pointing out the unique qualities of our pump, like he did the deficiencies of our pump and the unique qualities of his favorite.

Rapco enjoys exclusivity on checking vane wear on large pumps as the only manufacturer currently offering that option. That information would clearly benefit your readers that use the larger and much more expensive pump.

-Patrick White
President, Rapco, Inc.

In our report, we inadvertently used the phrase overhaul kit when we intended to say overhaul pump. The ad in question depicts a mechanic hanging inverted from the ceiling in a harness, attempting to inspect vacuum pump wear with a mirror and a flashlight.


In response to the Aviation Consumers November 2003 report on vacuum pumps, Aero Advantage would like to clarify the role of its dual-rotor vacuum pump in improving flight safety.

Dollars and cents: A dollars-and-cents analysis of the cost of safety will be forever debated. Comparing the cost of a dual-rotor pump to that of a single rotor pump is just plane misleading. They do not compete in the same arena. The single rotor is simply a source of vacuum, whereas, the Aero Advantage dual rotor unit is a self-contained, automatic back-up system, complete with monitoring capability. When compared to the cost of other independent back-up systems, the cost is quite attractive. On which would you rather spend your limited flying dollars, convenience or safety? You decide.

Oil seal design: Aviation Consumer writes a lot about oil seals in their discussion of vacuum pumps. Aero Advantage agrees that oil contamination is a leading cause of premature pump failures. The unique design of the Aero Advantage dual-rotor pump represents two very significant safeguards against these early failures.

Unlike the conventional single rotor design, the Aero Advantage pump has positive pressure in the area where engine oil, leaking from the accessory drive shaft, would enter the pump. The conventional pump design invites entry of leaking oil into the pump with the vacuum side of the pump being closest to the engine.

Furthermore, the Aero Advantage pump incorporates a contoured slinger oil seal, which is not only very effective, but also has infinite life since it has no rotating contact surfaces to wear out. To date, we have not had any known failures of an Aero Advantage pump attributed to oil entering the pumping chamber through the drive shaft oil seal.

Life predictions: All pump designs will, at sometime, experience premature unpredicted failures, even if they are inspected during use. After all, they are, by definition, unpredictable. To that point, the Aviation Consumer report concludes, rotational speed impacts the failure/wear rate but there isn’t always a direct correlation that either company can confirm.

During certification testing, the life difference between the two chambers of our certification pump was 68 hours, when running the pump to extinction. We did not set the 1000-hour overhaul time at the point of predicted pump extinction. Instead, we again took the conservative approach and built in a margin of safety so that sufficient pump life remains at the 1000-hour point.

Convenience: I was responsible for the limitation of not allowing the pilot to depart with one chamber inoperative and Im also working with the FAA to change that limitation in the STC to allow day VFR operations with one chamber inoperative. It was not done due to fear of the second chamber being ready to expire; it was done to give the utmost safety.

We have made the request to the FAA that the flight manual supplement be amended to allow day VFR operations with one chamber inoperative. Blame me for this limitation, not the dual-rotor vacuum pumps life prediction. To this end, a spare pump in the trunk is of little value when youre flying in IMC and your vacuum source fails. It does nothing to enhance safety of flight; its strictly a matter of convenience.

The above comments are not intended as criticism of anyones product. We are excited about the benefits of our built-in automatic backup feature and welcome the opportunity to communicate that to all who will listen.

-David A. Boldenow
Aero Advantage
General Manager

See “Which Back-Up Is Best?” in this issue for additional analysis of the Aero Advantage dual-chamber pump as a back-up system. While we agree that the dual pump is a safety advantage if the aircraft lacks either back-up gyro or back-up vacuum, we disagree that convenience shouldnt be a factor in this decision.

Anyone who has suffered the hassle of canceling a trip or riding the airlines home because of a failed vacuum pump knows the advantage of carrying along a spare pump in the baggage compartment. Technically, the Aero Advantage pump still doesnt address this issue, since an owner couldnt legally fly home on it in IMC, which is the entire point of having a vacuum system in the first place. We suspect many owners who opt for the dual-chamber pump will fly it home after a failure, STC limitation or not.


Headset Hassles
I purchased a Quiet Technologies headset for use in a Citation II and wanted to tell you about the customer service that comes with it.(See Aviation Consumer, February 2003, for the full review.) I sent several e-mail messages prior to purchase (Phil McCandless is the contact; his e-mail address is [email protected]) asking about performance in a jet cockpit, particularly the ability to hear warning horns.

Every message was answered immediately and thoroughly. I ordered the headset and it was perfect. Unfortunately, the headset is not TSOd (Mr. McCandless told me it was not TSOd before I purchased it) and it became a legal issue in the Citation, which is operated under FAR 135. The Chief Pilot reluctantly said it had to go, so I contacted Quiet Technologies about a return less a re-stocking charge. Ive used the headset for several months).

QT took it back with a full refund. I highly recommend the headset and commend them for their superior customer support before and after the sale.

-Name withheld by request


More on DVD
I second David Malins e-mail on DVDs in airplanes (Aviation Consumer, November, 2003, letters section) but I wanted to up it another notch.

The best set-up for airborne musical entertainment for my money is to buy an Apple iPod and plug that into your audio panels entertainment stereo jack. For the uninitiated, the iPod is a battery powered storage device about one-third the size of a VHS tape cartridge.The iPod can hold up to 40 GB of stored music or approx 500 CDs.

The iPod is a higher quality encoding/decoding device than the Asian-produced MP-3 players, which have trouble getting true stereo separation.

An iPod is portable, so the FAA doesnt need to be involved. Take it out of the airplane and plug it into your car for the ride home, or tuck it into your briefcase for the rare times you fly airlines and listen with headphones. Ive heard that VW is shipping their Bugs with an iPod cradle built in for this latest craze. For more information than you’ll ever need on these devices, perform a Web search with just iPod and you’ll see mounts, carrying cases and attachment devices that would cram a Sportys catalog.

I applaud PS Engineerings efforts to get their entertainment systems certified, but for tons less money, we can carry our whole music collection everywhere, even in store bought airplanes, without fumbling for CD and DVD disks. As to price, the 40 GB unit retails for $499, however the 20 GB iPod that sold for $499 nine months ago, can now be had for $349.

-Arthur J. Treff
Via e-mail