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SW Aviator Feb/Mar 2001
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Lighten Up

Portable Scales Offer a Viable Option in Meeting
New FAA Rules for Small Commuter Aircraft

By George Lindberg

For the Federal Aviation Administration (FAA), January’s crash of US Airways Express Flight 5481 in Charlotte, N.C., appears to have been one crash too many. In the days following the crash, which killed all 21 passengers and crew, FAA issued new rules relating to the weight and balance programs of carriers operating 19-seat aircraft under 14 CFR 121.

Pending the outcome of public comment, the FAA now will require commuter airlines to weigh all carry-on and checked baggage before takeoff, and may well have to weigh passengers instead of continuing to assume an average passenger weight of 175 pounds.

The FAA also is expected to waste little time before issuing more stringent rules regarding the weighing of general aviation aircraft. For FBOs, however, it offers an opportunity: Along with improving safety, aircraft weighing by means of portable scales would create a new revenue stream.

Whether the industry, particularly the regional airlines, resists the FAA remains to be seen. But no one who has investigated crashes disputes the dangers created when an aircraft are overweight or poorly balanced.

"I think it’s one of the things that may make commuter flying riskier, especially when you’re flying with a loaded airplane – the possibility that it could be out of weight or balance because of the distribution of weight,’’ said Jim Burnett, a former chairman of the National Transportation Safety Board .

The crash of Flight 5481 was merely the most recent of many crashes to be caused by poor weight and balance procedures, the FAA believes. In the case of the US Airways flight, preliminary NTSB evidence suggests the 17,000-pound Beechcraft 1900D was 100 pounds below its maximum weight and within one percent of the rearward limit for its center of gravity. Given those conditions, any miscalculation of the center of gravity that pushed unanticipated weight toward the rear could have made the plane unbalanced.

For any aircraft to take off, land, or fly at optimum conditions, weight must be evenly distributed. Otherwise the plane will burn more fuel than necessary to stay aloft and, moreover, its elevators and flaps will be inordinately stressed. As the name implies, the center of gravity (CG) is that point in the plane’s length where the craft is most perfectly balanced by the weight fore and aft of that point. When the fulcrum is in the center, the plane flies at optimum speed and pitch, saving fuel and protecting flight equipment in the process.

An aircraft’s balance is as important as its weight, particularly in smaller commuter turboprops and jets. In a MD-80 or 727, the CG range may be in a four- to five-foot area. In a Beech 1900, that range may only be 10 inches, which means there is little room for error in determining a commuter’s CG.

What the FAA wants now is for commuter operators to weigh their unloaded planes more than every three years and, more significantly, weigh baggage, freight, and passengers separately. Weighing passengers is key because old weight averages no longer apply, the FAA says. For years, airlines have estimated passenger weight by assuming an average male weight of 175 pounds. But since 1994 that weight actually has been 180 pounds. In addition, the size and weight of carry-on luggage has grown larger.

As the FAA moves to improve weighing procedures, many in the industry will argue that additional aircraft weighing, particularly when in-ground scales are used, is cost prohibitive. Air carriers already operate on thin profit margins, and higher equipment costs — along with fewer passengers or less freight — will cut into profits, the industry will argue.

When lives are at stake, however, that argument is moot. The public is not going to fly on an aircraft that hasn’t been proven safe, and those airlines that do not adopt better weight and balance procedures won’t be able to create a client base under any conditions.

Weighing aircraft to determine overall weight and CG is not as expensive or time consuming as many assume. In-ground scales don’t even have to be used. For years, the world’s largest airliners have used portable scales that have an accuracy rate well within plus or minus .1 percent. There are practically no advantages to using in-ground scales, which may cost five times as much as portable equipment.

Although more than one company manufacturers portable scales, the oldest and largest of them is Arlington, Texas-based General Electrodynamics Corp. (GEC). The firm also offers a weighing service used by the world’s major airlines. For nearly 25 years, GEC has offered a line of highly portable and accurate load-cell aircraft scales, and today also offers the only wireless aviation weighing system.

The price range for portable scales is rather broad, depending on how much weight and balance information is required. In general, prices range from about $10,000 to $25,000 for the highest-end systems, and most scales can be leased. All scales include multi-function indicators capable of calculating gross weight, CG in inches or centimeters, and percent of MAC. The results can then be printed out or, on the more sophisticated systems, read instantly on a hand-held monitor the size of a Palm Pilot.

Portable scales weigh as little 30 pounds and many are no larger than the average coffee-table book.
Contrary to popular misunderstanding, weighing an aircraft with portable scales takes only minutes, not hours. And one person can complete the process once the plane’s nose and rear gear are rolled onto the scales.

At least for a while, weighing a fully loaded aircraft is an improvement over the FAA’s plan. The current requirement is for all operators of 10 to 19-seat commuters to weigh their aircraft while empty, then weigh passengers individually or ask them their weight and add 10 pounds. The plane weight and assumed overall passenger weight then are added to freight and baggage weights, which also are obtained through separate weighing.

All of this separate weighing, coupled with the continued assumption of overall passenger weight, will not produce as accurate a weight and CG reading as would be obtained by weighing the aircraft after it’s loaded. If used even for a short term, the loaded-plane process would give operators more realistic data they could use if the FAA ultimately allows benchmark weighing to continue.

Whether commuter operators are willing to weigh passengers separately, or whether they will adopt the new FAA rules at all, remains to be seen. But there is one certainty: As America’s airline service becomes more regional in nature, the owners of commuter airlines will have to improve their methods of establishing CG and overall weight. Commuter aircraft aren’t like the largest airliners – for them, the margin of error is critically small.

Fortunately for all in the industry, the technology exists to make the aircraft weighing process simple and accurate. That should be a relief to everyone in the industry, given that the FAA finally has run out of patience with half-hearted weight and balance programs.

George Lindberg is vice president of Arlington, Texas-based General Electrodynamics Corp (GEC). He may be reached at 800-551-6038 or To learn more about portable scales visit the GEC web site at
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The material in this publication is for advisory information only and should not be relied upon for navigation, maintenance or flight techniques. SW Regional Publications and the staff neither assume any responsibility for the accuracy of this publication's content nor any liability arising fom it
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