We Fly: Blackhawk Aerospace King Air 350

How valuable are these mods to King Airs and other turboprops?

What aviation aficionado hasn’t watched the iconic 1986 hit movie Top Gun, the story of Maverick, a US Navy F-14 pilot portrayed by actor Tom Cruise? In an early scene with co-star Anthony Edwards, the pair is walking among a bevy of parked F-14s when Maverick’s overcome with the need to yell, “I feel the need—the need for speed,” in a high-fiving moment of excitement.

Sounds like most pilots, not to mention the people riding along with them. Flying brings great joy to all of us, but it’s also about traveling from one place to another—fast. Business aviation, in fact, is built around the need to turn useless hours on the airlines into productive time spent aboard a GA machine. That’s why pilots upgrade from a Piper Archer to a Beech Bonanza, then to a Baron or single-engine turboprop. Everyone wants to arrive just a little sooner while carrying more people and stuff.

Over the past 40 or 50 years, an entire industry of aftermarket modifications has emerged to squeeze every ounce of performance from airplanes of all sorts, especially for people who still love the airplane they already own or don’t want to spend the cash on a new one. There are often added bonuses to upgrading some airplanes: the increase in overall aircraft value and bringing it closer to the holy grail of modifications—making the airplane perform better than an original OEM machine at a far lower cost. By far, one of the most popular upgrades is switching powerplants.

Blackhawk Aerospace has created its own market for engine upgrades over the past 21 years through a knack for knowing which aircraft are worth the effort. The company has upgraded the engines on Cessna Caravans, the Cessna Conquest II and practically every King Air model Beechcraft ever produced, all using some version of Pratt & Whitney Canada’s venerable PT6 engine. Blackhawk also brokers turboprops of all kinds and offers in-house composite design, prototyping, building and certification services.

Blackhawk King Air 350
A Blackhawk King Air 350 even outperforms Beech’s new stock 360 in several parameters. Glenn Watson

The real value behind a Blackhawk product only emerges once a potential customer understands a bit of the company’s origins. The Waco, Texas-based performance-improvement company opened its doors in 1999, not long after founder Jim Allmon left his job with RAM Aircraft. He remembers talking to RAM Aircraft president Jack Riley. “I told him he had an amazing product, but that he should think about taking the company to the next level by doing upgrades to turboprops.” Allmon says Riley didn’t share his enthusiasm. “I decided it was time to go back out on my own, since I’d done it before.” So Allmon started buying and selling aircraft. He eventually ended up owning a local Waco FBO, a maintenance shop and a flight school with his two partners, Matt Shieman and Dale Griffin.

Allmon says the engine modification side of the business really began to take shape almost coincidentally when a friend approached him, suggesting he take an engine upgrade STC on a Cessna Conquest I that was in on trade for another airplane. Four or five months later, Allmon bought the STC. But he had to explain the market for engine upgrades he envisioned to his partners—which Allmon saw as a really big opportunity. “I told them I imagined a contract with Pratt & Whitney to buy new engines to manage this STC. I saw the PT6 as pretty much the plug-and-play engine.”

Both of his partners were CPAs and pretty financially conservative, Allmon says. “Both of them said they weren’t interested. ‘Show us a company out there doing this kind of thing.’” There wasn’t any company like Allmon was suggesting. Because he’s not the kind of guy to take no for an answer, Allmon said to them, “I believe in this idea and vision so much that I’ll sell you my stock in this company we have together and go out and do this on my own.” A move like that would have left his partners in charge of the FBO, shop and flight school—a proposition they weren’t all that thrilled about—so they agreed to give his idea a try. “It’s been a great partnership ever since,” Allmon says. To date, Blackhawk has purchased some 1,800 PT6 engines for aircraft-modification work. The company doesn’t handle all of the physical work in Waco, relying on a number of dealers such as Stevens Aerospace, Elliott Aviation, Ballard Aviation, Silverhawk Aviation and Textron Aviation to handle some of the load.

Blackhawk King Air 350
Demo pilot Paul Armstrong next to the PT6A-67A. Glenn Watson

Blackhawk’s latest package—the XP67A upgrade—swaps a stock King Air 350′s 1,060 shaft horsepower P&W PT6A-60As for 67As and replaces the standard four-blade Hartzell metal props with German-made five-bladed MT composite propellers. The upgraded engines are derated from 1,800 shp to 1,200 shp yet increase available horsepower on the modified airplane by 24 percent, allowing them to maintain rated power to the rarefied flight levels that produce much faster climb rates and higher cruising speeds.

Company-provided background material claims a modified King Air 350 is capable of a 60 percent increase in climb rate, a cruise speed of at least 332 ktas and a 62 percent increase in payload. The upgraded engines also carry an increased Pratt & Whitney warranty good for 3,600 hours. When it comes time to decide whether to modify, Pratt & Whitney offers a nudge in the form of engine core credits of up to $70 per hour per engine for every hour remaining up to the factory TBO. Blackhawk says operators flying at least 500 hours per year will experience a savings of $90,000 in annual operating costs. The company website claims, “Nearly every Blackhawk-powered aircraft sold within 500 hours of the upgrade recovered close to or more than the combined investment of the airframe and engines.”

Edwin Black, the company’s senior vice president of sale and marketing, answered some of the other questions often on the minds of stock 350 owners. “The price range [for the 67A upgrade] will vary depending on core-engine status. If you were on the [Eagle Service] plan from Pratt, the cost to upgrade can be as low as the $800,000 range. We have had 10 operators on ESP upgrade so far. If you are not on the ESP and the engines are timed out, a ballpark estimate is in the $1.8 million range (exchange). This compared to a typical overhaul cost of $800,000 for the first run, $1 million for the second run, and we have even seen three third-run overhauls in the $1.5 million range (for both engines). Point being: Never risk overhauling a third-run engine. And our price includes two new MT five-blade props.” Blackhawk says the time it takes to modify a King Air 350 with the 67A package runs about 2 to 3 weeks (10 to 15 working days).

Blackhawk King Air 350
Blackhawk replaces the original Pratt & Whitney Canada PT6As with a pair of brand-new flat-rated PT6A-67As, while five-blade MT composite props take over from the original Hartzell metal propellers. Glenn Watson

Putting XP67A Through Its Paces

We recently had an opportunity to put a modified King Air 350 to the test for an up-close look at the 67A modification. Paul Armstrong, general manager of SkyWest Aviation—also an A&P with inspection authorization—flew a King Air 350 up from Waco, Texas, and met me at Signature Flight Support at Chicago Executive Airport (KPWK). SkyWest Aviation operates N333HC for its owners.

N333HC was built in 2000, some 18 years before the then-owner made the decision to purchase the XP67A upgrade. Because the airplane arrived for the Blackhawk modification with a Garmin G1000 package, the upgrade also required turning the avionics into the Garmin NXi to ensure compatibility with the engines. The aircraft was also modified earlier with the CenTex fuel tanks.

Stepping into the cockpit of this King Air 350 was like a trip back in time because Beechcraft didn’t change much on its popular turboprop. Even relatively new, the airplane’s panel was still adorned with analog dials and toggle switches. The only clue you were inside an airplane built in the 21st century were those Garmin G1000 avionics. As Armstrong and I taxied to Runway 16 at KPWK, I noted the outside air temperature was at 32 degrees Celsius, or roughly 90 degrees Fahrenheit. There were three of us on board, including Blackhawk’s chief pilot Chris Duncan and about 1,250 pounds of fuel per side. The CenTex saddle tanks were empty. We calculated our takeoff weight at 12,470 pounds, about 2,500 pounds under maximum gross takeoff weight. With an empty weight of approximately 9,955 pounds and a useful load of 5,145 pounds, this airplane carries full fuel and still has room for 1,534 pounds of people and bags.

Blackhawk King Air 350
Fill the tanks on a Blackhawk 350 and carry eight people out of 4,000-foot strips. Glenn Watson

One reason there’s really no training needed after a Blackhawk upgrade is that all the standard takeoff and landing numbers remain the same; only the engine operating parameters change, keeping in mind that single-engine performance up high improves significantly. Blackhawk provides a complete flight-manual supplement highlighting the new cruise and single-engine performance. One item of note for longtime King Air pilots using the new propellers is the elimination of the low-pitch propeller stops. In the stock 350, weight on wheels makes the props automatically flatten out. Armstrong said one annoying issue was that the original props didn’t always change pitch at exactly the same moment, resulting in the airplane often wigwagging down the runway on landing. Now, the props change in a coordinated fashion on landing.

We filed an IFR flight plan northeast toward Traverse City, Michigan, to allow time to climb and evaluate the aircraft, but the lengthy segment turned out to be unnecessary because the airplane climbed so quickly. Remember, we were light. On takeoff, torque came up to about 80 to 90 percent with the propellers set to 1,700 rpm, knowing torque would eventually rise as we began the roll. By rotation, the engines were set at 100 percent. Once the gear disappeared, we pulled the props back to 1,600 rpm.

For demonstration purposes, Armstrong suggested an airspeed of 140 kias which translated into a deck angle of 10 to 11 degrees and a climb rate close to 4,000 fpm. He said he normally uses 160 kias for a deck angle near 7 degrees, which is a little more comfortable for people in back and for keeping an eye out for traffic, even though we were snuggly ensconced in the Chicago Class B airspace. The outside temperatures were quite a bit higher than ISA that day as we climbed toward 14,000 feet msl. I watched as the interstage turbine temperatures slowly began inching toward the magic 840-degree limit. Chicago Center briefly stopped us at 15,000 and turned us northwest toward Milwaukee before letting us continue to 17,000 feet.

Blackhawk King Air 350
Stepping into the cockpit of this King Air 350 was like a trip back in time because Beechcraft didn’t change much on its popular turboprop. Glenn Watson

Just to make things interesting, Armstrong pulled back the left throttle to idle to demonstrate single-engine climb performance, though we didn’t actually feather the prop. The OAT was ISA+18, and we were now cleared to FL 230. As we initially slowed to 140 kias, the rate of climb remained steady at 1,500 fpm. Armstrong said his preferred single-engine climb speed was 125 kias. As he let the aircraft seek that number, the climb rate eventually slowed to 1,200 fpm and stayed put through FL 220. “I can go practically anywhere in the US, and this airplane will climb on one engine,” he said. Think about that when you lose an engine in most other twins, especially if there’s ice or mountains hiding inside the clouds.

Diving into the updated aircraft flight manual, the data showed that at our weight, the aircraft would have continued on one engine up to FL 260. At maximum gross weight and ISA+20C, we could have made FL 240. Though the book shows no numbers above 24,000, Armstrong said, “I could fly it to 28,000 feet with just one [air-conditioning] pack” to maintain cabin pressurization. The King Air 350′s cabin rises to 10,000 feet once the airplane reaches its service ceiling of FL 350.

We added back the good engine as we headed to FL 290, our final altitude. Armstrong said, “Flight Level 280 to 290 is really the sweet spot with this airplane.” The ITTs remained steady at just under 820 degrees. “Although this airplane will run all day long at the maximum ITT of 840 degrees, I don’t run my engines too hard. I like 817 ITT in cruise. My rule is to run them 20 degrees shy of max unless I need it,” even though he says he won’t push them above 835 degrees, except in an emergency. “On a standard day, this airplane will average 2,500 fpm to FL 300,” he added.

Leaving FL 270, the airplane was climbing at 1,650 fpm. Once we reached FL 290, we let the airplane accelerate for about five or six minutes before pulling the propellers back to the standard cruise rpm of 1,500. It didn’t take long before I saw 333 knots of true airspeed. On a flight up high, say FL 320 or above, Armstrong regularly plans a fuel burn of 800 pounds the first hour and 700 for the second and third. The book says that at this same altitude on an ISA+20 day, but with the aircraft at max gross weight, cruise speed will slow to about 294 kias.

Blackhawk King Air 350
Blackhawk founder Jim Allmon and his two partners have, over the past 21 years, upgraded more than 1,800 Pratt & Whitney PT6-equipped aircraft. Glenn Watson

What Pilots Are Saying

Daniel Blazer and his dad both fly their Blackhawk 67A-modified King Air 350 in support of their retail and wholesale food company, as well as to keep an eye on their fleet of container ships. They’ll sometimes operate the airplane single-pilot and, at other times, with two pilots up front on trips that include legs between Atlanta and St. Petersburg, Florida (400 nm), and to ports along both coasts of Mexico (1,000 to 1,500 nm).

“We’ve owned a number of King Air 350s with the 60A engines on them,” Daniel says. When they began thinking about upgrading one of them—a 2012 airframe equipped with Garmin G1000 avionics—a deciding factor turned out to be Pratt & Whitney’s willingness to negotiate on core time as the engines neared another hot section, a strategy probably made easier by the airplane’s ongoing enrollment in Pratt’s ESP Gold program. The Blazers were one of the first to purchase the newest Blackhawk upgrade, and they used Elliott Aviation in Moline, Illinois, for the work, including upgrading their Garmin panel to the NXi version.

With a couple hundred hours logged on the new airplane, Daniel Blazer says: “This airplane climbs really nice through the mid-20s. The stock 350 started slowing just leaving 10,000 feet. Now we’re often climbing at 1,500 fpm up to the 30s where the fuel flows are running about 640 pounds total per hour. On the old airplane, we never cruised too high and often had to run the engine ice, which slowed us down even more. Now, we just use the engine anti-ice to climb through the weather. In cruise, there’s probably a 40-knot difference between the old airplane and the Blackhawk version.” Anything he wishes he could add to the Blackhawk upgrade? “The MT props don’t connect into the Beechcraft active sound-management system. It would be nice to figure out a way to make that work. But there’s nothing else really…except maybe I wish it would go a little faster.”

Paul Armstrong says the company for which he flies N333HC “was originally looking at [a Cessna Citation] CJ3+ for 1,800-mile trips. But some of our destinations require [that we operate out of] hot, high and short runways, and I was worried we might have performance issues in the mountains. In the [Blackhawk King Air], I can fill the tanks and take eight people out of 4,000-foot strips. It’s a monster as far as what it will haul. Jets cost two to three times more, and we’d only gain about 12 minutes an hour on a two-hour trip. This airplane with the 67As is like a whole new animal. Now we don’t need a jet. This is the most amazing plane I’ve ever flown. It really does what they say it will.”

This story appeared in the October 2020 issue of Flying Magazine

Login

New to Flying?

Register

Already have an account?