loading Loading please wait....

If you are a registered, please log in. If not, please click here to register.


Engine upgrades extend airplanes’ usefulness- utility and value

Dave Higdon   |   1st January 2006
Back to articles
Dave Higdon Dave Higdon

Dave Higdon writes about aviation from his base in Wichita Kansas. During three decades in...
Read More

Engine upgrades extend airplanes’ usefulness- utility and value.

Build a better mousetrap - the saying goes - and the world will beat a path to your door. Such was the case with the invention of the jet engine – though the journey towards that invention continued along a lengthy- arduous path. Even the business aircraft took time to catch on- evolving from converted utility aircraft through a reworked fighter before taking on the form now ubiquitous – the purpose-built executive aircraft we know today.

Fortunately for many operators- the capability of many business jets continues to evolve thanks to the ability to upgrade existing aircraft with newer systems.

No upgrade goes further to improve the operating characteristics and cost efficiencies of existing jets than those available for the engines.

For an operator in search of a budget-oriented path to upgrading their corporate wings- replacing the powerplants offers a route to operating and maintenance costs equal – or nearly so – to a plane newer than the budget could handle.

Let’s face it. Operating costs took a significant hit in the last year- thanks mostly to the price increases on jet fuel. Throw in the higher maintenance costs that often come as engines age- and those higher fuel prices make today’s older jets feel even harder to live with.

So what does a flight department do when feeling squeezed between newly higher operating costs and the big investment required for a replacement less costly to fly? Depending on the aircraft in question- upgrading an older business turbine aircraft with new power may be a potential resolution.

This decision can take the form of upgrading the existing jet or acquiring a similar aircraft already endowed with an upgraded powerplant. Thankfully for business aircraft operators- a number of cost-effective options exist that can make that old bird a new bargain- whether you’re already operating it or are looking to buy a used aircraft.

The payoffs

During the four decades since the first purpose-built business jets entered service- powerplants have steadily evolved- each generational advance bringing gains in all the right spots.

For example- weights declined as power outputs improved after engine makers found ways to produce ever more power from their products. Fuel efficiency also improved with each new engine generation thanks to growth in pressure ratios- increased operating temperatures and the decline in material weight.

Maintenance costs have declined with the expansion of engine-inspection cycles- advances that accompanied improvements in engine-trend monitoring- better materials and advanced manufacturing techniques. And the ability to manage power grew with the advent of technologies such as automatic starting systems and full authority digital engine controls (FADEC).

But what does all this mean to the operator – or prospective buyer – of a business jet already years old but with plenty of useful airframe life remaining? It means that for the long-term owner- an investment in an engine upgrade can translate into long-haul savings that can justify the up-front cost of the change.

Justifying such an expense essentially requires an assessment of the costs of continuing to operate an old airplane with its existing engine- including both the current age and maintenance and overhaul costs. Also necessary – a projection of how costs may escalate as parts grow in cost and shrink in availability in the future. The older an engine- the rarer its use- the higher such costs will likely go.

Maintenance cost savings alone can tally tens of thousands of dollars – maybe even hundreds of thousands – over the aircraft’s remaining life. Conversely- the maintenance costs of some replacement engines may never amount to more than routine maintenance over the remaining life of the airframe. The engines themselves may never reach a major overhaul period in that time – and that’s over 10 or more years of typical flying.

Plus- there’s the potential for further savings by enrolling those engines in some institutional maintenance programs – with the ensuing lower costs at fixed rates. And we haven’t even spoken of the savings accrued over those same years of burning fuel at rates reduced five percent; 10 percent; maybe even 40 percent.

Given the experience of the past several months- how likely do you think it is that fuel prices will go back down to their 2004 level? Clearly- opting for an upgrade to modern engines holds out serious cost-savings potential.

Faster- higher- shorter flights

Aside from the engine-specific cost advantages- an engine change offers savings in other ways- too. Take- for example- time-to-climb numbers. Climbing faster and more directly to cruise altitude can translate into lower fuel consumption in the climb phase- alone.

An engine upgrade often eliminates the step climb – that is- first climbing to a weight-limited altitude until fuel consumption brings down the weight to a point at which the plane can climb higher for higher speed and lower fuel burn.

Reaching optimal altitude faster means hitting the most-efficient altitude sooner- further enhancing fuel savings – particularly when the differences can run to 30- 40- even 50 minutes.

An engine upgrade may also result in higher cruise speeds- which also shortens trip times. With speed gains as high as 50 knots – or only 30 knots faster at economy-cruise power – the plane still gets to where you’re going faster…on less fuel.

Other benefits of an engine change come on the environmental front – both in reducing sound levels and reducing emissions. On the noise front- the improvements can reach the point of qualifying these older airplanes for operations into places where the old engine violates noise limits. In other words- the upgraded airplane enjoys more airport options – sometimes with the added benefits of shorter- cheaper flights.

And an engine upgrade can also present an opportunity to install upgrades in other areas.

If planned and executed properly- an engine upgrade can be integrated with a panel upgrade- interior- paint- or all of the above – essentially you can make the older airplane as modern as anything shipping today from Dorval or Toulouse- Savannah or Wichita.

Not every old airframe can gain a new life from a powerplant transplant- but for those that do- the range of options covers enough of the business turbine spectrum to offer an option beyond replacement with something not so new and more expensive – or something new and a total budget buster.


FJ44 Citation Eagle II

Cessna Aircraft revolutionized the business jet field with the introduction of the original Citation 500 series. Powering those new straight-wing business jets was an equally revolutionary new powerplant- Pratt & Whitney Canada's JT15D. Now regarded as a standard bearer in both reliability and safety- the engine powered an aircraft that opened up business jet ownership to a strata of pilots who otherwise had as alternatives several turboprop or piston twins - choices that came with slower cruise speeds and higher risks.

So attractive and useful were the original Citations that hundreds still fly as business aircraft. But over the ensuing decades Cessna developed a replacement for the earliest Citation that raised the bar on fuel efficiency- utility and costs: The CitationJet model- now known by its family name- the CJ1+- CJ2+ and CJ3. As with the first Citation- it was an engine advance that made possible the CJ line - the groundbreaking Williams Rolls FJ44 engine.

Texas-based Sierra Industries looked into the prospects of pairing a larger thrust version of that new CitationJet powerplant with early model 500 and 501 Citations- liked what they found- and put into motion the development of today's FJ44 Citation Eagle II.

Available through the South Texas based Citation modification company- the resulting Eagle II delivers performance that makes the conversion a competitive choice for owners of the older airframes - a straight-wing Citation 500 or 501 that rivals the newer CJs in terms of performance and fuel specifics.

The Eagle II upgrade replaces the Pratt engines with a pair of FJ44-2A turbofans making more than 2-300 pounds of thrust. The conversion also gives the Sierra FJ44 Eagle II a longer wingspan- higher gross weight and higher fuel capacity. These modifications significantly increase payload- range and flexibility compared to the same airframe in its original form.

And it's the blend of these upgrades that show where the conversion really shines. For example- the Eagle II boasts a top cruise speed as fast as 390 knots - a product of a thrust gain of about 40 percent up at cruise altitudes and the ability to climb direct to FL430. Of course- there's also a significant bonus in fuel consumption- down as much as 30 percent compared to the original powerplants.

Coupling the higher speed and lower fuel consumption with the longer wing also delivers significantly improved runway numbers and a longer maximum range of about 1-800nm.

Conversion prices vary according to the age and condition of the target airframe and any other upgrades undertaken- but at $1.6 million to $2.5 million for a completely refurbished 500 or 501- the Eagle II offers considerable value when compared to the prices of a comparable- new CJ1 or CJ2 - at around $4 million and up.

More information from www.sijet.com

Premier Aircraft

Falcon 50-4 Upgrade

For some missions and some operators- nothing less than three engines will do – the backbone behind the long- successful history of Dassault’s Falcon 50 tri-jet. Thanks to the efforts of Premier Aircraft- those Falcon 50s can gain new life and new efficiencies with an upgrade to the TFE731 Dash 4 engine.

According to Jim Swehla- president of Premier Aircraft- the Dash 4 conversion holds its strongest appeal to owners flying out of hot-and-high or hot-and-short-field airports.

For flights out of a 7-500-foot runway at 5-000 msl with a 90-degree OAT- the Falcon 50 Dash 4 can cover 26 percent longer distances than in its original form.

That said- the Dash 4 conversion also delivers other benefits with more universal appeal. For example- the Dash 4 conversion improves on the Falcon 50’s cruise range and its time-to-climb numbers – and who wouldn’t take those improvements.

Up high at cruise altitude- the 50 Dash 4 produces as much as 16 percent more power – an improvement translatable into greater speed and shorter flights- or lower overall fuel consumption at the old speeds.

Since the engine upgrade impacts the airframe only slightly- turn-around time is relatively short – as short as 45 to 60 days without loaner engines- or two weeks with rental-replacement powerplants.

The new engines are also more efficient thanks to a 5-000-hour inspection cycle- compared to the 4-200-hour cycle on the Dash-3 engines replaced during the conversion. Honeywell offers a three-year manufacturer’s warranty and lower rates for enrolment in its Maintenance Service Plan.

Premier Aircraft posts a retail list price of $2.305 million for three-engine conversions for an aircraft not enrolled in Honeywell’s MSP. For MSP clients who are approaching a compressor zone inspection ('CZI')- the modification can go as low as $1.6 million.

According to Swehla- who is also executive vice president of sales for Premier Air Center in East Alton- Illinois where the modifications are performed- the company already has received requests from five customers for letters of intent as of this writing. Final approval of the STC is expected later in 2006.

More information from www.50-4.com

Spirit Wing Gives Learjets New Life

If you missed it as a developmental program at the 2004 NBAA meeting in Las Vegas- you could have caught it at last fall’s NBAA convention in Orlando as an approved program. Either way- once again Williams’ FJ44 powerplant is giving new- improved life to a popular- older airframe – this time as Spirit Wing’s Learjet 25D.

It’s in how those engines make this airframe work that attracts owners and operators to this conversion of Learjet’s most-popular 1960s airframe. But it’s also the price that contributes to demand – in the low-to-mid $2 million area for a 25D that’s not merely re-engined- but also delivered as an RVSM-compliant business jet with many improvements over the original as it rolled out of the Wichita plant. For example- among the major improvements from the Spirit Wing modification is Stage 3 noise compliance- a whopping 50 percent drop in fuel consumption to about 800 pounds per hour at cruise- and an increase in useful load that’s enhanced by the removal of fuel capacity.

Removing the center fuel tank from the 25D still allows the converted airplane to fly about 1-700 nautical miles carrying four passengers – a gain of almost 70 percent over the original configuration with its payload-robbing center fuel tank.

In the case of the Spirit Wing engine conversion- the 25D loses about 100 pounds in thrust at take-off compared to the original engines - GE’s venerable CJ610-8A. Nonetheless- the smaller nacelles and the mounting also give the little Learjet a sleeker- faster appearance to go with its improved numbers.

More information from www.spirit-wing.com


Two Conversions Enliven Oldest King Air 90’s

Blackhawk Conversion

NBAA 2005 saw the emergence of yet another effort to enliven the oldest King Air 90s with new engines – this one from Texas-based Blackhawk Modifications.

Blackhawk- based out of Waco- acquired an STC that provides for the installation of Pratt & Whitney Canada PT6A-21 and -28 engines on the early 90 series King Airs (90s- A90s- B90s & C90s that were originally equipped with the older PT6A-20/20A engines). The six-year-old company is already known for upgrading newer King Air C90/A/B and E90s with the Pratt & Whitney PT6A-135A engines.

Headed by president Jim Allmon- Blackhawk saw an opportunity to provide a virtually unlimited number of low-time PT6A-21 and many PT6A-28 engines for the older King Air 90s. Because Blackhawk sells new PT6A-135A engines for the newer King Air models that are economically better suited for the Blackhawk XP upgrade- a nearly equal number of -21 engines come available through engine exchange.

All PT6A-21/28 engine cores Blackhawk receives in trade return to Pratt & Whitney- creating a growing pool from which the company can draw for other projects. Those engines- the company noted- have anywhere from 30 hours since new to near the 3-600-hour TBO – and most are on their first run engines and have very low cycle times.

By comparison- the majority of the 1960s-era PT6A-20/20A engines still flying are near their TBO. The overhaul cost of the PT6A-20/20A series powerplants can exceed the costs of newer PT6A models – potentially exceeding $350-000 per engine – rendering their economic life effectively over.

By switching to the PT6A-21 or PT6A-28 powerplants- the operator receives a newer-technology engine with improved hot and high power performance and vastly reduced maintenance costs – while costing much less than an overhaul of the older models.

Installation requires minimal changes to the airframe and is relatively simple and straightforward. The exhaust-stack openings in each cowl must be enlarged to accommodate the larger-diameter exhaust stacks of the PT6A-21 engines and optional replacement cowls are available.

The operator can also opt for Blackhawk to upgrade the engine instrumentation at the time of the conversion. Furthermore- all prop configurations are approved and installation can be done at any turbine shop.

Pricing for the project varies according to the exact time remaining on the -21/28 engines and any time remaining on the -20/20A cores. Upgraded aircraft carry a Blackhawk logo and the name- 'Blackhawk -21' or 'Blackhawk -28'- depending on the engine model employed.

More information from www.blackhawk.aero

Seagull Conversion

North of Texas in Wisconsin- Seagull Aviation offers a different take on upgrading C90- E90 and 100/A100-series King Airs - this one based on the widely available Walter M601E-11A turbine engine.

The engines used in Seagull’s conversion come with a thermodynamic rating of 705shp that’s flat-rated at 550shp to enhance engine life while still delivering power that’s a solid improvement over the original PT6 powerplants installed in the 1960s and 1970s King Air 90s.

The M601E-11A engine does not require nozzle maintenance or hot section inspections- and is equipped with an ‘Electronic Limiter’- which controls the engine start and eliminates hot starts. The Limiter is equipped to record starts so the engine can be monitored by the maintenance base.

Seagull’s conversion option offers more power and greater performance- as well as longer inspection intervals and vastly lower overhaul costs. The conversion also includes a modern- quieter- five-blade propeller that produces higher thrust across the operating range.

According to Seagull- its conversion option for the C90 operator could save hundreds of thousands of dollars in maintenance costs. The converted C90 will cruise at 232 kts TAS @ FL250- and loaded up- will still climb 900 fpm through FL250.

The 100/A100 conversion- meantime- offers operators improved speed and climb performance- and greatly reduced engine maintenance costs. To date- Seagull has completed four C90s- a 100 and two A100s.

Walter Engines offers each customer a set of tools with each engine- and a kit with the consumable items needed to complete the required inspections from installation to TBO. The engine overhaul costs $70-000-75-000 per engine which Seagull points out with an average 3-000-hour TBO- equates at an average cost of about $25 per hour- per engine.

Conversion costs can- of course- vary- depending on other work desired at the time. Depending upon the value of the engines being removed from the aircraft being converted- Seagull has done complete conversions for $195-000 to $305-000 using the old engines and propellers as trade-in value.

Empty weights do grow to accommodate the higher weight of the engines and props - the C90 conversion includes a 450 gross weight increase to 10-100 lbs.

The M601E-11A engine has a 3-000-hour TBO or eight year calendar life. Seagull’s pitches it’s program as a cost effective alternative for the King Air operator who wants more power and better performance at a savings of $200-000-500-000 in engine costs over an overhaul cycle.

More information from www.seagullaviation.com

Loose Ends

Piaggio’s upgrade to the PT6A engines on its Avanti 180 led to the creation of the Avanti II now selling out production – and owners of original Avantis can have the same improvements in power- climb and fuel consumption thanks to an available retrofit for those airframes.

Other airframes have been re-engining targets but failed to reach critical mass; and entrepreneurs continue to look for airframe-and-engine-conversion prospects that hold both commercial promise and operational benefits. So don’t consider this feature all-inclusive. If the idea is breathing into your bird new life with new engines- check with your maintenance crew or surf the list of Supplemental Type Certificates for your jet or propjet.

If you find the benefits worthwhile and the numbers reasonable- you just may find a way to keep your old airplane a viable business aircraft for many more years.

Related Articles

linkedin Print

Other Articles