8

KA300 continued from page 1

new King Air are 23.5 kt fast er , 1,5 00 lb heavier, 400 m ore shaft horsepower and almost a half a million dollars more expensive than its Model B200 predecessor.

The flagship-to-be uses the same fuselage, empennage, and virtually the same wing as the B200, but larger and longer Pratt & Whitney of Canada turbines. The longer engines are more tightly cowled than those on the B200 and they project 5.2 in. further forward in front of the wing whose inboard leading edges have already been extended five inches to provide more wing area .

The engines, PWC PT6A-60As, carry a maximum sea level rating of 1,113 shp, but are mildly flat rated to 1 ,030 shp in the Super 300. Th ey spin four-blade 1 05-in. diameter Hartzells which turn at a slow and quiet 1500 rpm for all normal modes of cruising flight .

Standard, the airplane weighs 9,290 lb, providing a useful load of 5 ,8 10 lb at its max gross take­off weight of 14,000 lb. Fuel capacity is 539 gal which , at 6. 7 lb per gal, translates to 3 ,611 lb . (Usable fuel in the Super 300 is five gallons less than the 544 gal in the Model B200. The capacity was reduced 2Yz gal per side to allow for the larger main landing gear system.)

"Typically equipped," said Beech in its introductory an-

nouncement, "the 300 is the only jetprop in its class that offers its operator the flexibility to fill the fuel tanks, fill the passenger seats, fill the baggage space to its 55 0-pound maximum, and still operate easily within the airplane's center of gravity and gross weight limi­tations. "

Standard seating is for seven passengers- in six individual chairs and a belted potty seat opposite the entry door.

In addition to greater payload/ range flexibilities, the Super King Air 300, according to its specs, offers improved speed and climb over its B200 sibling. Despite more weight and power and 5 gal less fuel , range of the 300 is roughly equal- no doubt due to lower sfc's of its PT6A-60As. Where a B200 owner stepping up into a Super 300 may find inhibiting differen­ces is in the latter's operating re­quirements. By reason of its SF A R 41 C certification, the Super 300 will present him with operating limitatio ns that may re­strict his choice of airports. When operated above 12,500 lb under FAR 91 and at all weights under FAR 135 , the Super 300 will have to adhere to accelerate-stop and accelerate-go distances for takeoff ; moreover, it will have to meet the climb gradients of a transport category aircraft. But for FAR 91 operations at 12,500 lb or under, the Super 300 need only conform with the less restrictive criteria in FAR 23 . As the table shows, the rather long accelerate-stop is one of the less creditable performance

Aviation Convention News

traits of the Super 300. Both its 3,682 ft with approach flaps and 4 ,854 ft with no flaps are consid­erably longer than the accelerate­st ops for the Citation I and 11 at their mgw and S.L./ ISA.

T he Super 300's listed accel­era te-stop distances were determ.in­ed using the ground fine (beta ) mode of its propellers along with, of course, brakes as stopping aids. T he pow er lever quadrant on the Super 300 differs from that of the B200 in that it has two ramps. Lifting the levers over the first puts the props in ground fine; lifting them over the second puts them in reverse.

Since there is so much com­monality between the Super 300 and B200, it may t ake even sea­soned professionals some time to tell them apart. The tight cowls on the long PT6A-60A engines that power the new airplane are the main features that distinguish it from its older sibling. Beech calls them "' pitot cowls ," to point out that their small er (70 vs 88 sq in.) inlet area creat es sort o f a pitot effect that provides much better recovery of the inlet air. The efficiency in this r egard, said Beech, is 9 5 percent.

Other improvements on the Super 300 vis a vis the B200 are its hydraulically operated landing gear (the B200' s is electric) and its three-bus electrical system of­fering another avenue of redun­dancy over the two-bus system in the B200.

The landing gear doors fully enclose the wheels of the Super 300. While this is so on the B200 with standard tires, it is not so when the 200 is equipped with the large tires available for it. The Super 300 uses a tire size that is intermediate between the standard and the large on the B 2 00 .

As mentioned, the wing of the Super 300 is "virtually" the same

as that on the B200. One dif­ference is tha t the inboard leading edges have been extended forward about five inches to provide more wing area. " We wanted to keep stall speeds almost identical to the Model 200," explained a Beech spokesman . The extended chord of the wing center section m oved the e.g. range three inches further forward than in the Model 200.

Another wing-related change has been the addition o f a strake on each side of the fuselage , where it meets the front part of the outer wing sections. The reason is said to be for improved stability.

One of the most significant differences between th e Super 300 and the B200 is one that Beech , for a variety of reasons, did no t mention in the descrip­tion of the airplane in its press releases. T his is a new main spar design and a new method by which the main spar of each o uter wing is connect ed to the central main spar.

As King Air operators well know, the spar connection has been both a sensitive and con­t entious subj ect and is currently

Except for slightly more wing area in the center section, the new Super of the King Air clan, the Model 300, shares the same airframe as the 8200, but new en­gines have added a big increase in shp.

the underlying cause of two law­suits. Critics of the way the main spar has been connected claim this is a failure-prone design. Beech admits that there have been two instances of breakage in one of the bolts that has held this spar to­gether, but attributed one of these instances to bolt corrosion. It staunchly maintains there has never been an accident caused by struc­tural failure in a Super King Air.

FAA did issue an AD requir­ing periodic inspections of the spar attach fitt ings on King Airs, and Beech offers Inconel steel bolts which lengthen the time of the mandatory inspection to five­year intervals.

In its Super 300, Beech bit the bullet and redesigned both the main spar and its attach fitting. (See accompanying box.) The de­cision, however , seems to have put the company in a difficult posi­tion, particularly in view of the on-going litigation. If it points out the advantages of the new structure and connection, this could be in­terpreted as tantamount to admit­ting that the previous design (as in the King Airs from the B 200 on down, and before them, the Beech 99 and D 18 series) was wrong and this is actually a correction. As a result , the company apparently has decided to say nothing-publicly , at least - about the significant structural change between the Super 300 and B200, which potential buyers and current King Air operators would most certain­ly want to be made aware of.

98

King Air Briefly, the redesign (explained

more fully in the box ) involves a change in the lower main spar sec­tion from a single- to a three­element unit, plus a change in the lower spar cap bolt from a t ension to a shear type .

Asked if this change would be introduced in forthcoming B200s, a Beech spokesman said the com­pany had no such plans at this time. He said that the reason the change was made o n the Super 300 was because of its additional weight .

Notwithstanding the denial, strong rumors continue to circu­late that Beech will soon go from a tension to a shear bolt in the lower cap of the main spar in its Model 200. Beech President Linden Blue appeared to have ad­mitted as much when he respond­ed to a direct question at the Beech King Air Maintenance & Operations session at the last NBAA Convention. At the time, Blue's questioner said that he understood the change would take place in B200 S/ N 1193 . Current­ly, S/N 1180 is the next one due to roll off the company's B200 pro­duction line in Wichita.

Performance is the strong suit

of the new Super King Air. It touts a top speed of 317 kt (23 .5 kt faster than the B200) and, at max range power, can fly 1,960 nmi with 45-min reserves. Climb rate from sea level at max gross weight is 2,844 fpm, while single­engine climb under the same con­ditions is 867 fpm. Two-engine service ceiling is "above 35,000 ft," while being 22,878 ft on one

·engine. At max gross, the Super 300

will clear a 50-ft obstacle after takeoff in 2,803 ft with flaps re­tracted. With approach flaps (14 deg) it will top the same obstacle in 2,203 ft .

The airplane's rather long accelerate-stop distances have been mentioned. This, of course, is without reverse thrust. With reverse, the stopping distance would be considerably shorter, however, since this is not a certi­fication test item, Beech has no official figures for this maneuver.

External noise on takeoff, said Beech, was measured as 72.07 dbA, well under the FAR 36 limit, although higher than the 6 8. 8

Aviation Convention News

dbA estimated for the B200, as listed in FAA's latest Advisory Circular 36-3C.

For the Super 300's list price of $2,341,750, the buyer receives a full complement of IFR avionics, including Collins Pro Line II nav­com and Sperry Primus 200 color radar. The autopilot and flight directors are extra cost items. Collins APS-65 with FDS-84 and Sperry SPZ 4000 with FTI 400 are offered, as well as EFIS from both companies in lieu of electro­mechanical flight directors.

The buyer also receives a newly designed interior that is claimed to be quieter and to have improved aesthetics, as well as more responsive heating and cool-ing systems.

The passenger chairs have been redesigned to provide more ef­ficient use of space and better

body support. Each seat has an inflatable lumbar adjustment and will track laterally, fore, and aft, and will recline. Arm rests stow under the seat when not in use, effectively providing more cabin room.

Not all the sedentary ingenuity of Beech interior designers went into the passenger seats. Crew chairs have been redesigned, too. In addition to being tiltable 2.5 and 5 deg, they have inflatable lumbar supports and infinite posi­tion arm rests. Also making life on the Super 300's flight deck simpler, the pilots' oxygen masks now store overhead instead of be­hind their seats. Another nicety: shoulder straps for the pilots can now be released without having to detach the seat belt, too.

The pilot's window that is in the B200 has been eliminated, as have been those metal pieces that conduct cold air into the cockpit. In the Super 300, the pilots com-

8,2·~;~~.1 b efl1Rn'>' ."1 ;. )~ •. 1PO-Ib1 r~mp wt;J14,ooo7·:s·. · lb t.o ;~wt. ; max cru1se. power at 28,000 ft. In- , eludes allowance for fuel for starting, taxi, climb,

. . descent, and 45-min reserve at max range power ,. ' ., ,,.AV' 'j: . . ;'. ~j<, .··. . .~~<, , ·" · . :&'''', ' Yz

pants· (incl. 'crew) plus 839 lb baggage and 3 ,611 l'b fuel be-fore engine start:

.,

1AQO.omi 4 t\'r, 38 n1 in 302 kt 1 oa.9 gp~/6.96 PPh

:._~· :~%~·, ; ;;,;.:~/ '' ' ,'C:.,~ : . ,

2. 15 occupants (incl. crew) plus 660 Jb baggage and 2,600 lb f tjel before

953 nmi 3 hr, 11 min .2

municate with the ground crew through an interconnect near the nosewheel-just like in the airlines.

Still another flight deck im­provement: flight and engine in­struments are now lit internally, instead of by post lights.

Cabin heating and cooling have been improved. There's a two­position switch that regulates the amount of bleed air entering the cabin, and there are electrical heating units at the front and rear of the cabin to expedite warming on cold days while on the ground.

For those who prefer numbers, the dual bleed-air heating system has 45,000 ·BTU capacity, while the cabin air-conditioning system is rated 22,000 BTU.

New techniques and materials are used in the cabin interior to make the installation lighter in weight, more sound absorbent, and to give it a more spacious aura. Nomex honeycomb, for example, is used in the cabin furniture and bulkheads, and a formed foam material constitutes the interior shell. To minimize vibration and the sounds it gen­erates, all of the interior items save for the seats, are mounted on rubber isolators.

Other interior improvements include overhead indirect lighting, from the cockpit to the rear bag­gage area; redesigned interior cabinetry ; a new stereo system with overhead speakers; tables between facing chairs that have magnetic game boards, particular­ly adaptable to the checkers and chess sets that are part of the standard equipment provided with the airplane.

Like its B200 predecessor, the Super 300 is approved for flight in moderate ICing. Its standard equipment includes flush fuel vents, engine control heat blan­kets, engine inlet screen anti-icer protection system, exhaust­heated engine inlet lips, heaters, electric prop anti-icing, wing ice lights, dual windshield electric heat, wing, and horizontal tail de­icing boots and brake de-ice .

Beech will have a Super 300 demonstrator flying in April. It ·declined to say what it has set for an initial production rate for the airplane. Its B200 production has slowed to a trickle because of high field inventories. There are be­lieved to be at least 3 0 unsold new King Air B200s at Beech's factory and in the hands of dealers. 0

.SUPER KtNG AIR 300 PER FOR MANCE

Stall Speeds (at 14,000 lb, idle power) Flaps up Approach flaps Flaps down

Climb on 2 engines (S.L.) flaps up flaps up approach flaps approach flaps .,~ ..... ,.

T .O. wt. limit (14,000 lb at 5,000 ftl flaps up approach flaps

Takeoff distance at 14,000 lb flaps up decision speed (V 1 )

obstacle speed (V2l ground roll distance over 50-ft obs.

approach flaps decision speed (V 1) obstacle speed \V2) ground roll distance over .so~rt obs.

_i,_ "'

Accelerate-stop d .istao'ce af14,000 lb (includes. 2.2 sec allowance for failure recognition and reaction) flaps up:

dec ision speed distance

approach flaps: decision speed distance

Accelerate-go d istance at 14,000 lb

100 kt 90 kt 81 kt

2,844 fpm (1 4,000 lb) 3,277 fpm (12,500 lb) 2,656 fpm (14.000 lb) 3,073 fprn {12,500 IIJ)

867 fpm (14,000 lb) 1,074 fpm (12',500 'Ib)'

I• .. .. . ..

41.9-deg C 31.9-deg C

110 kt 120 kt

2,042 ft 2,803 ft

97 kt 107 kt

1,576 ft 2,208 ft

105 kt 1,686 ft 21907 ft

110 kt 4,854 ft

97 kt 3,682 ft

(includes 1.2 sec-allowance for failure recognition) flaps up:

decision speed obstacle speed .· distance over 35 ft. obs.

f laps approach : decision speed obstacle sp~~~ ';: .... ·c .;.

distance:·over -'tf5 ft. 'obi

110 kt 120 kt

4,349 ft

97 kt 107 kt

3.700 ft

Beech's Super 300 tightly wraps its PT6A-60A turbines in "pitot cowls" having only 70 sq in. of inlet area, but the 95-percent ram recovery efficiency allows the engine to thrive on less air.

THE KING AIR CONNECTION In all King Airs, the wing is composed of three sections-a

center section that extends from about six inches outboard of one nacelle through the underside of the fuselage to about six inches outboard of the opposite nacelle; and two (left and right) outer wing sections. Each outer wing section is joined to the cen­ter section by the simple process of bolting their respective front (main) and rear spars together- t wo bolts per spar connection, four bolts per side, and eight bolts for connecting both wings.

(The front and rear spars are 1-beams formed by joining a T­beam to an inverted T-beam (_L). The mass of the 1-beam of the front spar is about double that of the rear 1-beam because the front spar carries t he lion's share of the load.)

In all King Airs prior to the Super 300, the spar connections are made by so-called "tension" bolts. This is because the bolts run parallel to the leading edge of the wing and, because of this placement, any bending loads on the wing spar generate tension stresses in these bolts. Consequently, the name "tension" bolts.

Because of the almost constant upward forces on t he wing, the bottom bolt of the main spar is almost always under tension stress in f light. Of the four connecting bolts per side, this is iden­tified as the most critical one.

Even though the bottom bolt of the rear (secondary) spar ex­periences tension stresses as well, t his bolt is not a critical item, since it is said to carry only about one-fifth of the total bending load. The rear spar's main reason for being there, according to one structural engineer familiar with the King Air design, is to complete the wing tors ion box-i.e., to prevent the w ing from twisting.

In the Super 300, the .critical lower bolts for the main spar connections have been changed from tension to shear. The new connection, made possible through the use of multi-element spar terminations changes the bolts' direction 90 deg, so that they

now run parallel to the fuselage. The change causes bending loads on the spar to manifest themselves as stresses in shear and not in tension.

Only the bottom bolts con1ecting t he main spars have been changed in the Super 300, all other six bolts-three on each side - remain t he same as in the Super 200.

In add ition to the change from torsion to shear bolt, the lower section of the main spar has been changed from a single element inverted T to an inverted T composed of three elements-the cen­tral vertical element (spar web), joined to two 90-deg angle beams, one on each side of the web. The three elements (looking, some­what, like JIL ) are bonded together (under pressure and heat) to form the inverted T-beam that becomes attached to the single­element upper T-section of t he main spar to form the 1-beam.

Having three elements in the critical lower spar section pro­vides three, in lieu of one, crack propagation path.

"Any one of the three elements could fail and the spar would remain intact," expla ined a Beech spokesman, who pointed out that the design is both safe-life and fail-safe.

The main spar from the center section terminates in three ''fingers," each having a centra~ bolt hole. These mesh with two similar "fingers" from the outer w ing main spar. The shear bolt is then inserted through all five fingers and fastened.

The arrangement is analogous to the hinge on a door where the ' tangs on the two hinge pieces are fitted together and the hinge

pin inserted. "Keepers" on t he shear bolt in the Super JOG's lower spar con­

nection prevent it from moving forward or aft, so that even if it fractured, t he lower main spar connection would be maintained.

So confident is Beech of its new spar/spar-connection design, that it intends to start its Super 300 off with an initial wing-life of 30,000 hr. 0