After your cost to acquire an airplane, the single largest expense is aviation fuel. Does improving 2.5 Nautical Miles Per Gallon offer significant savings? Cirrus optimized the SR22TN Turbo-normalized for efficient fuel flow (10 years ago), which does lower total cost of ownership.
Reason 22 – Cost of Ownership: Fuel Expense NMPG
Based on manufacturers’ brochures the Cessna Corvalis TTx is 21 knots faster than the Cirrus SR22TN, but the Corvallis burns more fuel with a lower NMPG performance.
| Aircraft | NMPG | GPH | CPH | KIAS |
| Cirrus SR22TN-G3 | 12.20 | 17.60 | $88 | 214 |
| Cessna Corvallis TTx | 9.80 | 24.00 | $120 | 235 |
| Variance | 2.40 | (6.40) | $(32) | -21 |
Reference: WhyCirrus.com, Aircraft Comparison Marketing Brochure, 2013
Here’s a simple illustration to compare the fuel cost difference. If a Cirrus SR22TN were flown for 2,000 hours at the manufacturers’ touted 214 KIAS the plane would travel 428,000 thousand nautical miles. If the Cessna Corvallis TTx were flown at its 235 KIAS it could cover 428,000 miles in 1,821 hours but look at the difference in total fuel costs (see table below).
NMPG Comparison Total Fuel Cost ($5.00 per gallon)
| Aircraft | NM | Hours | CPH | Cost Fuel |
| Cirrus SR22TN-G3 | 428,000 | 2,000 | $88 | $176,000 |
| Cessna Corvallis TTx | 428,000 | 1,821 | $120 | $218,553 |
| Variance | $(42,553) |
The more efficient Cirrus SR22TN results in a fuel cost savings of $42,000 or about the price of a new TCM IO-550-N engine. For our European aviators the cost difference is even higher at about $75,000. The fact is, neither manufacturer will have pilots flying their turbo planes at 25,000 feet and maximum cruise speeds for 2,000 hours. But the point remains – nautical miles per gallon matters.
Most owners will fly their turbos in the mid-teens and still enjoy high airspeeds. In the mid-teens, Cirrus still beats the competition on total fuel cost and closes the margin on airspeed.
So why are manufacturers not improving piston engine efficiency? How long must we wait for the next improvement? Will Cirrus innovate on the piston engine again? Teledyne Continental Motors or Tornado Alley Turbo? Tornado Alley Turbo is suppose to release a new digital density controller for improved waste-gate performance.
It’s been ten long years. Will the next innovation happen in our lifetime?
Pilots and passengers want safety and performance in an airframe package that provides generous cabin comfort. We also need best in class NMPG performance.
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