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April 2000

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March Board Meeting

The USA Board met on March 22. The following is a synopsis of that meeting.

First, the Board itself has changed. Karl has resigned as Treasurer. I know this was a difficult a decision. The post of Treasurer is perhaps the most demanding position on the Board, and Karl performed it very well. Thank you, Karl, for a job well done.

Heidi Alley was asked to fill in the remainder of the year as Treasurer and she has graciously accepted. Thank you very much Heidi.

On to the business at hand.

Membership Dues:

The cost of club membership has been raised to $420 per year or $35 per month starting with the billing in May.

Associate membership dues have also been increased to $100 per year, and a change has been made which doubles the hours associate members may log in club ships to a total of fourteen.

The reason is simple: Club dues have not increased since 1980, but in the past twenty years the costs of insurance, maintenance, even tie-downs have risen with inflation.

The Gliders:

The 2-33 has been painted (it looks fantastic) and is sitting in Lee’s storage facility.

The Grob is still down in Jean. It’s tire isn’t leaking badly, but it will get a new tube on assembly day. The radio is still an issue (the display seems to have a short) so we should pull it out and send it to a repair facility. Soaring magazine lists a couple and it looks like we’ll send it down to a place in Miami. The glider will be flown/trailered home over the April 29, 30 weekend.

The Grob needs some work on the canopy hinge-to-gelcoat connection. This will be done during the first week of operation.

All of the gliders will be trailered (at various times) up to Morgan so that Wayne and his crew will have a chance to complete the annual inspections prior to the May 6 assembly date.

Safety:

The club “currency” rules have been made more stringent. If you have not flown (either glider or power) in the last 45 days, you must have a check out with the club instructor. It is thought that the old “currency” period of 90 days is too long.

Various:

The World Wide Web has become a powerful advertising and communication tool. To help streamline new membership application, the club will soon post an automated application on the web.

The Board is looking into installing club “banners” with the club logo and the web site on the tail surfaces of it’s gliders similar to those displayed by Soar Utah.

We are looking into having polo shirts embroidered with the logo.

The club dinner/awards ceremony will be complete with plaques this year. The categories will be Total Air Time, 2-33 Air Time, Farthest Distance, “Sod Buster” Award and a Club Thanks.

2000 Calendar

May 6 - Glider Assembly Day
June 10 - Summer Picnic
July 8 - 15 - Nephi Week
September 16 - Fall Picnic

PIO and Grobs

by Dean Carswell

In the last twelve months, there have been several reported cases of substantial damage to Grob sailplanes arising from the pilot's failure to control the glider correctly during the flare and touchdown phases of landing. Both the two-place G103 and single-place G102, with nose-wheels, are prone to the problem of pilot-induced oscillation (PIO). Here is an example taken from a recent NTSB factual accident report [amended to remove identifiable references]:

". . . a Grob G103 was substantially damaged during landing. The certificated private pilot and passenger were not injured. The pilot stated that the purpose of the flight was to conduct a local area glider flight. He estimated the winds at the time of the accident to be 270 degrees at 10 - 15 knots. The sky was reported as clear. The pilot departed from Runway 23 and released from the tow aircraft at 3,000 feet above sea level. The pilot stated that he searched for thermals, but found none, and that he remained within two miles of the airport until he decided to abort the flight due to insufficient lift. After deciding to abort the flight, he positioned the aircraft on a left downwind for Runway 23 at 800 feet above the ground. From downwind, he turned onto the base leg, and then final approach approximately 500 feet from the approach end of Runway 23. According to the pilot, it was the last flight of the day, so he planned to land long. It was the club's policy to land long on the last flight of the day because the glider was to be tied down at the opposite end if the runway."

The pilot stated that while on the final approach, he had his hands full just to keep the glider lined up with the runway, and that the ride was very bouncy. According to the pilot, he carried approximately ten knots of extra airspeed while on final because of the turbulence. He did not recall his exact airspeed, but estimated it to be approximately 70 knots. The pilot added that the glider touched down at the intended touchdown point, but bounced back into the air. He stated that after the first bounce, he was focusing on maintaining runway alignment [so] that the glider started to oscillate from the Pilot Induced Oscillation.

After contacting the runway a total of four times, the pilot was able to regain control of the glider and complete the landing. The pilot estimated that from the point of initial contact with the runway until he regained control of the glider was approximately 500 feet.

The pilot inspected the glider and found the tail-wheel crushed into the tail of the glider. He also observed several cracks in the tail that penetrated the gel-coat and the underlying fiberglass.

Dissecting what occurs in a Grob PIO can be instructive. There are two scenarios which usually precede arrivals such as the one reported. The first occurs when the glider touches down on the main-wheel and bounces back into the air. The pilot pitches the nose down and the glider strikes the nose-wheel resulting in the nose pitching up rapidly.

The second scenario occurs when the nose-wheel of the glider touches the ground first [the flare is initiated too late]. The nose-wheel strikes the ground and causes the nose to pitch up rapidly. Alternately, during the flare the pilot may raise the nose up too far, then pitches the nose back down. The nose-wheel then strikes the ground followed by it rapidly pitching up again.

What happens next is that the nose pitching up causes the tail to pitch down, striking the ground. After the tail strikes the ground, the glider pitches nose down again, striking the nose-wheel even harder. This process continues in a divergent oscillation which increases until something else occurs - usually, and all too often, structural failure just ahead of the fin unless the pilot takes action to correct the oscillation.

In the first case, it's simple - neutralize the controls after the first bounce - the glider will level out above the ground. Do not force the nose back down on or towards the ground. If the glider has bounced or climbed just a few feet, it will sink at a relatively gentle rate, and safely back to the ground of its own volition. If it is a BIG bounce, gently lower the nose and this time flare at the correct height. If the airbrakes are more than one-half open, gently closing them a little will allow additional time to flare correctly. Remember that lowering the nose decreases both angle of attack and lift, causing the glider to sink quite rapidly. Consequently, any forward stick movement must be gentle.

In the second case, damp out the oscillation motion - i.e. pitch down gently (stick moving forward) as the nose comes up, and vice versa. When the oscillation stops, centralize the controls and let the glider land itself (as in Case One). DO NOT FORCE the nose back onto the ground. If for any reason the glider continues to oscillate (if your timing is bad and you aggravate the oscillation), neutralize the controls and apply full airbrake. This will quickly reduce energy and stop the glider from flying, even if in a rather unpleasant and abrupt manner. It is less likely to cause damage than permitting the oscillation to continue unchecked.

The undignified and possibly expensive method of arrival can be avoided by:

1.Establish the landing approach at the correct airspeed for the conditions. The greater the airspeed, the greater the pitch sensitivity.

2.Establish the landing approach with half or more airbrake (the more the airbrakes are closed, the less pitch stability the Grob will have, making a PIO more likely if otherwise mishandled).

3.Flare at the correct height. Don't fly the glider into or force it onto the ground. Aim to arrive with low energy, touching down with the main-wheel and tail-wheel simultaneously.

It should be noted that a correct approach (i.e. preparation for the flare and touchdown) is important in preventing this problem. Fly the correct approach speed (not too fast or too slow) using at least one-half airbrake, thus eliminating the pitch instability. These simple steps will greatly reduce the problem and risks of pilot induced oscillations.

Total Maintenance Tips

What goes through your mind just prior to the departure role? Mine is "What happens if the tow line breaks?" Going into my trusty spring refresher mode, I recently reviewed chapter 10 of Transition To Gliders, by Thomas Knauff. This chapter is entitled, "Premature Termination of the Tow." Below I will attempt to enlighten you with some of the highlights. These include not just rope breaks.

A premature termination of a tow can occur in a variety of ways.

1. Rope break

2. Engine failure for the tow plane (partial or total).

3. Release mechanism failure (tow plane or glider).

4. Accidental release (passenger or pilot of glider or tow plane).

5. Fire or smoke in tow plane (real or imaginary).

6. Bird strike, bee sting, or other critter problem

7. Ground loop.

8. People and/or pets running out onto the runway.

9. Discovery of forgotten preflight time, such as failure to hook up controls.

10. Others I haven't thought of.

As stated above, anything can happen on tow. The most critical period is during the first 600 feet of altitude gain. Your chances increase greatly with more altitude under your belt. We are trained, that in zero to light wind conditions, we can release from tow at 200' AGL and land back at the airport. As the winds on the ground increase, add altitude to your checklist to keep all options open. The grass is a great alternative if the active runway is occupied. If you are below the necessary height to return to the airport, land ahead.

Knauff's book is a good one and if you don't have it, I highly recommend adding it to your aviation library.

Happy Landings!!

Paul Schneider

X-C Insurance

Or... a Sunday drive through the Heber and Kamas valleys.

Let me get a few things clear right off the bat:

1. The owners may get pretty upset by a glider landing in their field, emergency or not.
2. Even a fantastic description is a poor substitute for your own emergency land-out preparations.  I suggest you use these pitiful notes as fuel for your own Sunday drive.
3. That fantastic looking field in March may be totally unlandable in June.
4. I don't know jack about landing out.

Heber:

I wanted to concentrate on an LZ I might use coming back from the Uintas having gotten over the ridge which separates the two valleys without enough altitude for home.    Can you say "target fixation"?  I knew you could.

Heading toward the mouth of Daniel's canyon at the junction of Rt. 40 and Mill Road there is a very nice field to the west.   A local farm house flies a flag.   Approximate position: N 40 28' 28", W 111 23' 42"

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3600 E. heads north off of Center Creek Road.  About .7 miles up you can see some pretty nice fields east of the road.  Approximate position: N 40 29' 16.5, W 111 21' 26"

Kamas:

If there's just no way I can make it back I wanted a couple options as close to the east mountains as possible.  The pickings are better over here, but many of the fields are subdivided by fences.  I selected two.

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Just north of Woodland on the western corner of the main road and Gines Lane there is a nice field.  Approximate position: N 40 35' 23", W 111 14' 32"

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About a mile south of Kamas on the eastern corner of the main road and Page Lane there is a nice field.  Approximate position: N 40 37' 34", W 111 16' 50"

David Lane

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