Cessna 425 Corsair / Conquest I

This page's frontmatter describes the Cessna 425 as built at 8,200 lb — serial numbers 425-0001 through 425-0176, 176 of the 236 airframes on the certificate. The later S/N 425-0177 and On airplanes are 8,600 lb, and so is any earlier airframe modified by Cessna service kit SK425-17, which is the modification the FAA itself says causes the airplane to "be renamed Conquest I". Both blocks are in the Variants table with their own numbers.

The 425 is a pressurized Cessna 421 Golden Eagle re-engined with Pratt & Whitney Canada PT6A-112 turboprops, and B/CA's January 1981 pilot report puts it exactly that way before adding the qualification that matters:

At first glance, the 425 Corsair is simply a 421 Golden Eagle reengined with Pratt & Whitney PT6A-112 powerplants. As you know, however, nothing is simple in a major redesign and new certification. … the transition from recip engines to turboprop power required structural redesign in the fuselage, wing and empennage.

It shares TCDS A7CE with the piston twins it came from — the 401, 402, 411, 414 and 421 — as Section X, and it is the only turbine airplane on that certificate. Cessna sold it as the Corsair from 1980 and renamed it Conquest I for the 1983 model year, when the maximum takeoff weight went from 8,200 lb to 8,600 lb.

The defining engineering decision is the flat rating, and it is why this airplane behaves unlike most light turboprops:

The Pratt & Whitney PT6A-112 is flat-rated to 450 shp each in the Model 425. Basically the -112 is the same engine that powers Piper's Cheyenne I (the PT6A-11), but in the Piper installation it produces 500 shp.

The rather dramatic flat rating in the Cessna installation increases the altitude at which full power can be drawn. For example, in the 425 installation the engines can produce rated takeoff thrust to 17,700 feet …

most light turboprops realize their fastest cruise speeds at relatively low altitudes, usually between 10,000 and 14,000 feet, where fuel specifics are relatively poor. The Corsair's maximum cruise speed of 264 KTAS occurs at 17,700 feet.

So the 425 is a high-altitude airplane that is unremarkable down low and excellent up high. B/CA measured it against the competition of the day: at 12,000 ft the Cheyenne II is 30 knots faster and the King Air F90 18 knots faster; at 18,000 ft the Cheyenne II's lead is down to nine knots; and at 25,000 ft "the Cessna airplane takes the lead and becomes the fastest (and most fuel-efficient) of the group."

This page was split out of a conflated cessna-425-441 page, which named two airplanes on two different type certificates in one model field and scored both of them with the 441's numbers: 10,165 lb, 475 gallons, 1,270 shp, a 49.3 ft wing span and FL350. A 425 is 8,200 lb on 366 gallons and 900 shp, spans 44 ft, and is certificated to 30,000 ft. It also cited A25CE and A33CE — the Cessna 404/406 certificate and a hot-air-balloon certificate — neither of which has ever covered a Conquest.

Everything else is common: PT6A-112s at 450 shp each, 366 usable gallons, 30,000 ft maximum operating altitude, 6 to 8 seats, 230 kt VMO and 0.52 MMO. Maximum landing weight is 8,000 lb on every airplane in the line.

NOTE 7 is the FAA explaining Cessna's marketing, verbatim:

Model 425 (S/N 425-0001 thru 425-0176) are eligible for the maximum weights and C.G. Range applicable to S/N 425-0177 and On, when modified in accordance with Cessna SK425-17, and will be renamed Conquest I.

So "Corsair" and "Conquest I" are not different models — they are one certificated model on either side of a service kit. On any specific airplane, read the records rather than the name on the paint.

The heavier block retires its wing 900 hours earlier. TCDS A7CE NOTE 3 sets structural retirement lives, and they key on the same split:

A retirement life is not an inspection — it is a hard number of hours after which the part must be replaced or the Cessna SK425-48 kit installed on the schedule NOTE 3 lays out. On a 45-year-old airframe this is a pre-buy item, not a footnote.

The cruise triple comes from one row of AOPA's December 1984 box, and that row is flown at the weight this page stores:

Cruise speed/Range w/45-min rsv, std fuel at 8,200 pounds (fuel consumption, ea engine) @ max cruise power, 26,000 ft — 251 kt / 1,240 nm (203 pph / 30.3 gph)

"ea engine" is the sentence that stops a two-times error. 30.3 gph is per side, so the airplane burns 60.6 gph and the frontmatter stores that.

The economy row from the same box, at the same altitude and weight:

@ max range power, 26,000 ft — 213 kt / 1,560 nm (152 pph / 22.7 gph)

That is 45.4 gph combined for 1,560 nm — 320 nm further for 38 knots. It is not in the econ_* frontmatter fields because the schema requires a percent-BHP figure alongside them, and neither a free-turbine engine nor AOPA quotes one.

Two other speeds worth keeping straight, neither of which is the stored cruise:

• 264 KTAS at 17,700 ft — B/CA's maximum cruise speed, at the top of the flat rating. No fuel flow or range is published with it, so it is not stored.
• 220 kt at sea level, 260 kt at 18,000 ft — AOPA's maximum level speeds, which are not cruise settings at all.

Climb. B/CA quotes the flight manual at 2,027 fpm at max gross (8,200 lb in January 1981) and adds a real-world data point: "Starting at 1,500 feet at 7,400 pounds, we made it to FL 250 in 11 minutes, 37 seconds," against the AFM's 16 minutes from sea level. AOPA's 1,875 fpm is the same airplane 400 lb heavier. Best rate of climb is 115 knots, which B/CA notes restricts forward visibility over the long nose; 135 knots still gave 2,000 fpm.

Single-engine performance is the flat rating's other dividend.

We should note that one of the real advantages of the large flat-rating margin is extraordinary single engine performance at altitude. The Corsair's single engine service ceiling is 18,500 feet at max gross takeoff weight.

Sea-level single-engine climb is 380 fpm at 8,600 lb, and B/CA measured about 500 fpm at 13,000 ft at 7,000 lb.

Pressurization. No psi figure is published in either source. What B/CA gives instead is the practical one: "At 25,000 feet, where the Corsair's cabin altitude is 10,000 feet…". The conflated page's "5.0 psi differential" is not carried forward because nothing obtained states it.

Handling is the airplane's reputation and both reviewers say so.

Pilots, in our opinion, will like the way this airplane handles. High or low speed, high or low altitude, one or two engines, the Corsair is in every way a pleasure to fly. Stalls are docile and grandly announced by much rumbling and buffeting.

Ground handling may be best in class. … we doubt any pilot will have problems taxiing the 425 or controlling it during takeoff or rollout-even in gusty winds.

Pattern speeds are modest — 150 to 130 knots downwind, 120 base to final, 100 over the fence — and autofeather is standard equipment.

A note on the runway numbers. AOPA's box is explicitly "at sea level and gross weight", and its gross weight is 8,600 lb, so the 2,110 ft ground roll, 2,420 ft over 50 ft, 940 ft landing roll and 2,120 ft over 50 ft all describe the heavier airplane. They are conservative for the 8,200 lb block this page stores. The accelerate/stop distance is 3,800 ft and accelerate/go 3,360 ft — the numbers that actually size the runway for a turbine twin, and both longer than either takeoff figure.

Built on 8,200 lb gross, AOPA's 4,922 lb standard empty weight and 366 usable gallons (2,452 lb of Jet A).

Full fuel and a full cabin is not on the menu at 8,200 lb. 826 lb is four adults and almost nothing else, and a well-equipped airplane will be heavier than AOPA's standard empty weight — the box's own "as tested" airplane was 5,327 lb, which leaves 421 lb over full fuel, or two people. AOPA's own full-fuel payload line for the 8,600 lb airplane reads 1,300 lb standard and 896 lb as tested.

This is the strongest argument for the 8,600 lb block, and it is worth being plain about: the extra 400 lb of gross weight buys 374 lb of useful load, which is two more people with full tanks. If a specific airframe has SK425-17, that is worth real money.

The realistic business mission is four to six people, 200 to 250 gallons, FL240 to FL260, 251 knots and 700 to 1,000 nm — which covers most of what an owner-flown turboprop is actually asked to do.

• Business travel (9): The core mission and the reason the airplane exists — a step up from a 400-series Cessna without leaving the brand. Pressurized cabin-class comfort, six seats in a club layout with refreshment centre and potty, single-pilot, FL250 to FL300. It loses a point to the 441 on range and payload rather than on comfort.
• Cross-country (8): 1,240 nm at 251 knots with 45 minutes of reserve, or 1,560 nm at 213 knots. Genuine transcontinental capability with one stop.
• Cargo hauling (5): 3,278 lb of useful load and 1,100 lb of certificated baggage across four stations, but no cargo door and a cabin sized for people. B/CA notes the nose compartment takes skis and golf clubs.
• Surveying (5): Stable, quiet and efficient high, but the fuel burn penalizes long loiter and the cabin has no camera provision as standard.
• Backcountry (2): Retractable gear, low wing, 2,420 ft over a 50-ft obstacle and turbine maintenance infrastructure. Wrong airplane.
• Flight training (1) and aerobatics (1): Not suitable.
• Local fun (2): Direct operating costs are four figures an hour.

Factory panels are early-1980s Cessna 1000-series or Collins remote-mounted equipment. B/CA was unusually positive about the standard fit:

The aircraft we flew had Cessna's 1000-series integrated flight control system. … We were especially impressed with the IFCS. It performs with all the finesse and agility of the most expensive systems.

AOPA, three years later, was not:

Sperry's SPZ-500 autopilot system is a new option that any potential buyer should consider-this is due to the fact that the standard ARC 1000 autopilot is one of the weaker links in the Cessna 425's systems.

Either way, a 1980s panel is obsolete for ADS-B and for modern IFR. Typical upgrade tiers today:

• Entry: legacy panel, a single Garmin GTN 750 or dual GTN 650s, GTX 345 ADS-B, original autopilot still in service.
• Mid: Garmin G600 TXi, GTN 750Xi/650Xi, a modern autopilot where an STC exists, Garmin weather radar.
• Top: dual TXi displays with synthetic vision, a modern digital autopilot, fresh paint and interior, mid-time or Blackhawk engines.

RVSM is not a question on this airplane, unlike the 441 — the 425's certificated ceiling is 30,000 ft, below the RVSM floor.

• Cessna SK425-17 — the maximum weight and CG kit that takes an early airframe to 8,600 lb and renames it Conquest I. On the certificate, in NOTE 7.
• Cessna SK425-48 — the wing kit NOTE 3 requires when an airplane reaches its wing retirement life. The compliance schedule is in NOTE 3 and depends on hours already flown.
• Blackhawk XP engine upgrade — replaces the PT6A-112 with the PT6A-135A. Widely fitted and a significant value driver. Note what this does to the numbers on this page: every performance figure here is a -112 figure, and a -135A airplane is a different airplane for cruise, climb and hot-and-high work. reference/engine-overhaul-pricing.md prices the -135A at $358,000 per engine against the -112's $370,000.
• Known ice is an installed-equipment finding rather than a standing property of the type: TCDS A7CE grants it "when ice protection equipment is installed in accordance with Cessna Drawing 5914105 for 425 … Factory Kit (FK) No. 194, POH and/or FAA Approved AFM". Verify it on the specific airplane.

• Parts availability: good but not excellent. Textron still supports the type and the airframe shares a great deal with the 421.
• A&P familiarity: specialist. The PT6A is the best-supported turboprop in the world, but the airframe's structural retirement lives and the pressurized cabin need a shop that knows cabin-class Cessnas.
• Engine reserve: $370,000 per engine at 3,500 hr TBO, from reference/engine-overhaul-pricing.md, which is P&WC's own published P&WCSMART flat rate — the strongest cost figure in this catalogue. On a twin that is $740,000 for the pair, or about $211 an hour for the airplane.
• Hot section: $65,000 per engine at half TBO, the PT6A class figure.
• Maintenance program: Cessna's Cescom programmed maintenance was offered from 1982 and later moved to a continuous inspection cycle over 600 hours or 18 months rather than the original 200 hours or 12 months.

See Maintenance Ecosystem and Engine Overhaul Pricing.

Prices on this page are legacy and unsourced; no current Vref or Bluebook figure was obtained for the 425. What is sourced is history, and it is worth recording because it frames the depreciation:

AOPA also noted in December 1984 that "in the last four years, the price spread between the two Cessna turboprops has grown to $670,000" — the 425 was always positioned well below the 441, and it still is.

The three things that move a 425's value today: engine time and whether it is a Blackhawk conversion, panel generation, and wing hours against the NOTE 3 retirement life. The last of those is the one a buyer is least likely to think of and the one with no ceiling on the bill.

See Aircraft Valuation Methodology.

Two airworthiness directives are named in the December 1984 AOPA article and are recorded here as leads for a records review rather than as a compliance list — no FAA AD database check was run in this pass: one concerning improperly drilled windshield mounting holes, and one requiring replacement of the nose gear actuator rod end.

The certificate itself sets the hard items, and these are not optional:

• Wing retirement life — 10,200 hr at 8,200 lb, 9,300 hr at 8,600 lb, per NOTE 3, with SK425-48 as the remedy on a defined schedule.
• Lower wing carry-through main spar — 12,500 hr.
• Wing carry-through — 30,000 hr.
• Windshield — 13,200 hr on the 425's own part numbers (5111604-3/-4 and -202/-203), and on the heated 9910460-1/-200.

Known service issues from the 1984 AOPA account, which is a contemporary owner-experience report rather than a maintenance manual:

• The torque indicating system is the airplane's weak point. The original wet gauge system has fourteen fittings prone to leaking, and leak-checking it "averages 20 man hours of labor". An electrical conversion exists.
• Hot section cost was addressed by a revised fuel nozzle configuration that reduces heat concentration on the burner can during starts.
• Fuel bladder and pressurization components are the usual age-related squawks on cabin-class Cessnas of this era.

Pre-buy must cover wing and carry-through hours against the retirement lives, which weight block the airplane is on and whether SK425-17 was ever installed, engine trend monitoring, and the known-ice equipment list.

• Hull values in the $600K–$1.2M band drive premiums of roughly 0.5–0.9% of hull annually. The stored $8,000 is a legacy figure.
• Training: initial type-specific school at SimCom or FlightSafety is effectively required by underwriters, with annual recurrent typically mandated.
• Minimum experience: underwriters generally want four-figure total time, meaningful multi-engine time, turbine time and a current instrument rating.
• The transition is the 425's selling point. B/CA judged it "close to the best (if not the best) handling airplane of this class in the approach and landing modes", and Cessna designed it so that "handling characteristics and systems … facilitate quick and safe transition by piston-twin pilots". A 421 owner moving across is a better underwriting risk than the hours alone suggest.

See GA Insurance Underwriting.