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Beechcraft magnesium flying controls

The TB 30 uses fabric covered controls, to save weight and thereby if I understand correctly boost the flutter speed. Same concept but older and arguably better technology.

If obtaining magnesium replacement skins is truly problematic, carbon fiber replacement skins are lighter than magnesium and I suppose that might work in a ‘black magnesium’ direct replacement scheme. The skins could anyway be produced fairly easily. Apparently you have to use the right kind of rivets to avoid corrosion.

A lot of things could be done if the STC process was amenable.

Last Edited by Silvaire at 22 Nov 16:00

Silvaire wrote:

A lot of things could be done if the STC process was amenable.

Agree entirely and frankly this again all boils down to liability law and the manufacturers unwillingness to move. Bit like TBO on engine/motor hours.

A solution will be found and the problem will vanish, but there will be a cost where the customer will pick up the tab.

Fly safe. I want this thing to land l...
EGPF Glasgow

Peter wrote:

Titanium is OTOH a really amazing material. Perhaps one could use it for the skin?

If money is no object, probably!

I opine that the choice of magnesium for some Beechcraft control surfaces was probably influenced by designers who had used it in military aircraft designs they’d been involved with previously. It made the plane more efficient, at a monetary expense. At the time of manufacture of the plane, that cost difference was not that great, and the extra processes for corrosion protection were easily accomplished. Decades later, in the field, maintenance is not so easy. And remember that no GA airplane manufacturer intended for their planes to be flying this many years. So they’re not rushing to produce low cost replacement parts, it’s an “it costs what it costs” situation.

The change of product by STC is certainly possible, and I have approved different skins on Cessnas. But the balancing of flight controls, and subsequent testing for approval is a daunting task. In the next couple of weeks I have some flutter testing to do during approval flight testing of a Grand Caravan with a wing mod. The new expectations for active flutter testing imposed by the regulator are really burdensome. In this regulatory world of caution, would make it a big job to approve different flight control skins. It can be done, it’s just costly. One by one, airplane owners cannot bear the cost. Legacy airplane owners need to organize themselves into type clubs, and have the club bear the approval cost on behalf of all of their members for the desired mod.

Exotic materials are just that, exotic, and usually not appropriate for GA planes. Keep it as simple and common as possible to keep maintenance costs down in the future. Cessna and Piper lead the market in building compromise planes, and they are, but en mass, they’re still flying, where other more exotic types were not economical to maintain. Recent ADs on both Cessnas and Pipers are showing the concerns of aging airplane structures – but those planes served well past their intended lives to begin with….

Home runway, in central Ontario, Canada

Surely, labour cost dwarfs the material cost, of e.g. 0.8mm rolled titanium sheet. Re-skinning an elevator is a seriously skilled job which needs to be done very accurately otherwise you get trim issues which will never be solved – see e.g. this. The average Part M workshop has little chance of doing it properly, IMHO. There was a long report here somewhere on somebody re-skinning a TB20 wing and it took him for ever, and he really knew what he was doing.

Shoreham EGKA, United Kingdom

Apparently Beechcraft is possibly going to produce replacement ruddervators as an OEM part, at the possibly ‘reasonable’ $9,000 a piece. You need two by the way.

I doubt they can make money on this, so it may be an act of ensuring the brand integrity is protected. In all its variants there are over 10,000 Bonanzas/Debonairs still out there.

Oxford (EGTK)

At 9k, their gross margin will be in excess of 95%. Yes, $8.5k gross profit. That is how the “TC owner” business model works. They buy the material for ~nothing, and use their TC + 145 + in-house-DER / Easa21 cert to produce certified parts. Socata do this all day long; even bought-in parts often come from obscure French homebuilder-market vendors (one sometimes finds them in a far corner at EDNY). Of course you don’t make 95% gross on a whole plane but that’s because (a) you buy in most parts for $lots and (b) you pay for months of labour.

The challenge is to sell enough to make it worth the documentation / tooling effort. But the fleet size is huge; few GA fleets are bigger.

Shoreham EGKA, United Kingdom
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