The light business jet category starts here. Bill Lear built the Model 23 on the bones of the FFA P-16, a Swiss ground-attack fighter that never reached production, keeping its thin high-speed wing and turning the rest into a six-passenger twinjet.
First flight came on 7 October 1963, the FAA type certificate followed on 31 July 1964, and 101 airframes were delivered before the Model 24 replaced it in 1966. The 23 runs 18×5.5 10-ply tubeless main tires and an 18×4.4 10-ply deflector nose tire, sizes it shares with every Learjet 20-series airframe that followed.
Learjet 23 Specifications
| Manufacturer | Lear Jet Corporation, Wichita, Kansas |
| Type | Light business jet |
| First flight | 7 October 1963 |
| Certification | FAA type certificate issued 31 July 1964 under CAR 3 |
| Entry into service | 13 October 1964 |
| Production status | Out of production. Built 1964 to 1966 |
| Units built | 101 |
| Engines | 2 x General Electric CJ610-4 turbojet, 2,850 lbf thrust each |
| Max range | 1,591nm (1,830 statute miles / 2,945km) at maximum fuel |
| Cruise speed | 450 kt normal cruise. 518 mph at 40,000ft |
| Max speed | 488 kt (561 mph / 903 km/h) at 24,000ft |
| Service ceiling | 45,000ft |
| Rate of climb | 6,900 ft/min |
| Takeoff distance | 3,393ft |
| Landing distance | 3,310ft |
| Max takeoff weight (MTOW) | 12,499 lb (5,669 kg) |
| Max landing weight | 11,880 lb (5,389 kg) |
| Empty weight | 6,150 lb (2,790 kg) |
| Wingspan | 35ft 7in (10.84m), including tip tanks |
| Length | 43ft 3in (13.18m) |
| Height | 12ft 7in (3.84m) |
| Wing area | 231.2 sq ft (21.48 sq m) |
| Seating | 2 crew plus 6 passengers |
| Used market (2026) | No functioning market. One airworthy example worldwide, with the rest in museums or long-term storage |
| Operating cost | No current benchmark. CJ610 fuel burn and Stage 3 hush kit compliance dominate the economics |
Learjet 23 – History and Overview
Development and Background
The P-16 was a Swiss attempt at a jet ground-attack aircraft that lost its production order after a run of prototype accidents. Bill Lear looked at the wreckage of that program and saw a wing and a structural concept worth buying. He set up the Swiss American Aviation Corporation to build a twin-engine executive version, designated the SAAC-23 Execujet.
The operation moved to Wichita in February 1962 and became Lear Jet Corporation. Hank Beaird and Bob Hagen took the prototype up for the first time on 7 October 1963, and certification came on 31 July 1964. Under ten months from first flight to type certificate is a pace no clean-sheet business jet has matched since.
The prototype was lost on 4 June 1964 when a spoiler deployed inadvertently during a go-around. The second airframe carried the certification program through, and the first customer delivery followed on 13 October 1964. Production ran to 101 aircraft before the Model 24 took over.
Design and Performance
A maximum takeoff weight of 12,499 lb is not a coincidence. It sits one pound under the 12,500 lb threshold that triggers heavier certification and crew requirements, and the whole airframe is built around staying there. Empty weight is 6,150 lb, which leaves a genuinely useful load for the category.
Two CJ610-4 turbojets of 2,850 lbf each give 6,900 ft/min of climb and a 45,000ft ceiling. The 23 climbed faster than anything else carrying passengers in 1964 and still outclimbs most of what shares the airways with it today. Cruise is 450 knots, with 488 knots available at 24,000ft.
What the wing does not have is leading edge devices. Approach speeds are high, the stall is abrupt, and the type earned a reputation among pilots for demanding respect rather than offering forgiveness. A drag chute was standard equipment, which tells you most of what you need to know about the landing roll.
Variants
- SAAC-23 Execujet: the original designation under the Swiss American Aviation Corporation, before the program moved to Wichita in February 1962.
- Learjet 23: the sole production variant, built 1964 to 1966. 101 airframes including the prototype lost in June 1964. No sub-variants were certified.
- Learjet 24: the 1966 successor, certified to the more demanding FAR 25 standard with a 13,000 lb gross weight and improved pressurization. Shares the 23 landing gear and tire sizes.
- Learjet 25: a stretched 1967 development seating eight passengers, again on the same wheel and tire fitments.
- Hush kit conversions: Stage 3 noise compliance retrofits for the CJ610, developed long after production ended and the only route to continued US operation.
Operators
Corporate flight departments and early fractional and charter operators took almost the entire production run. Frank Sinatra was among the first private buyers, and the type carried enough celebrity traffic in the mid-1960s to make Learjet a generic term for a business jet within a few years of the first delivery.
The 23 also recorded one of the better-known fatal business aviation accidents when a 1970 crash killed United Auto Workers president Walter Reuther. Air taxi operators continued to fly surviving airframes through the 1970s and 1980s. A handful went to government and research users, but there was no meaningful military order.
Current Status
Production ended in 1966 and the fleet has been shrinking ever since. By 1998, 39 aircraft remained operational and 27 had been written off. US Stage 2 noise rules finished the job: the CJ610 cannot meet current limits without a hush kit, and for most owners the retrofit cost more than the airframe was worth.
As of 2025 a single airworthy Learjet 23 remains, N477K, the 36th airframe and a 1965 build, fitted with hush kits for Stage 3 compliance along with RVSM, ADS-B and TAWS. Preserved examples sit at the Pima Air & Space Museum and in the Smithsonian National Air and Space Museum collection. Tire support is not a constraint, since the sizes remain in volume production for the Learjet 20, 30 and 40 series.
Learjet 23 Landing Gear and Tires
Landing Gear Configuration
The 23 uses a hydraulically actuated retractable tricycle undercarriage with a single wheel on each leg. The main gear retracts inboard into the fuselage and the nose gear forward, with oleo-pneumatic shock struts throughout. Wheel and brake assemblies carry over largely unchanged into the Model 24 and Model 25.
Everything about the braking case is harder than the aircraft size suggests. A thin wing with no leading edge devices means high approach and touchdown speeds, a 12,499 lb airframe arrives with real energy, and early airframes were delivered without the anti-skid systems later jets take for granted. The standard drag chute exists precisely because the wheel brakes alone were working at their limit.
Tyre selection follows from that. Both positions are 10-ply tubeless at a 210 mph speed rating, and the nose carries a deflector pattern that throws standing water and slush outboard rather than up into the fuselage-mounted intakes. Non-deflector tires exist in the same 18×4.4 size for other aircraft and are not interchangeable here.
Learjet 23 Tire Specifications
| Nose wheel tire size | 18×4.4, deflector (DDT) type |
| Main gear tire size | 18×5.5 |
| Ply rating | 10PR nose / 10PR main |
| Construction | Bias ply, tubeless |
| Speed rating | 210 mph typical at both positions |
| Tire pressure | Refer to the aircraft maintenance manual |
| Compatible brands | Goodyear, Michelin |
| Part numbers | Main: Goodyear 185F03-5, 185K03-1; Michelin 033-631-0, 026-631-0. Nose: Goodyear 184F03-2, 184F10-2; Michelin 031-613-4, 027-613-0 |
| Common fleet | Same sizes fitted to the Learjet 24 and Learjet 25 |
Always verify tire size, ply rating and part number against the aircraft’s maintenance manual, illustrated parts catalog and applicable airworthiness directives before ordering. Serial number, installed modifications and hush kit or gross weight changes can affect tire requirements.
Main Gear Tires
The 18×5.5 10-ply tubeless main is the published fitment for the Learjet 23, 24 and 25 in Goodyear’s application chart. Goodyear covers it with the Flight Eagle 185F03-5 and the Flight Leader 185K03-1, both rated to 210 mph. Michelin offers the Air 033-631-0 at 210 mph and the Pilot 026-631-0 at 190 mph.
One substitution trap is worth naming. The same 18×5.5 size exists in an 8-ply, 120 to 190 mph form used on light piston types such as the Cessna 337, and those part numbers are not eligible here. Check the ply rating and speed rating together, not the size alone.
Nose Wheel Tire
The nose takes an 18×4.4 10-ply tubeless deflector tire. The chine on the sidewall deflects water and slush outboard, which matters on an aircraft with its engines mounted on the aft fuselage directly in line with the nose wheel spray. Goodyear lists the Flight Eagle DT 184F03-2 and the Rib DDT 184F10-2 in this size and rating.
Michelin 031-613-4, 031-613-8 and Air 027-613-0 cross-reference against the same group, as does Goodyear 184F13-5. The 6-ply and 12-ply 18×4.4 tires on the market belong to other aircraft and should not be fitted. Confirm the deflector configuration in the parts catalog before ordering, since the size designation alone does not tell you whether a tire is chined.
Approved and Compatible Brands
The following tires are listed in the sizes and ratings fitted to the Learjet 23:
- Goodyear Flight Eagle 185F03-5: 18×5.5, 10PR, 210 mph, tubeless, main gear
- Goodyear Flight Leader 185K03-1: 18×5.5, 10PR, 210 mph, tubeless, main gear
- Michelin Air 033-631-0: 18×5.5, 10PR, 210 mph, tubeless, main gear
- Michelin Pilot 026-631-0: 18×5.5, 10PR, 190 mph, tubeless, main gear
- Goodyear Flight Eagle DT 184F03-2: 18×4.4, 10PR, 210 mph, deflector, nose gear
- Goodyear Rib DDT 184F10-2: 18×4.4, 10PR, 210 mph, deflector, nose gear
- Goodyear 184F13-5: 18×4.4, 10PR, 210 mph, nose gear
- Goodyear 184F08-1: 18×4.4, 10PR, 190 mph, nose gear
- Michelin 031-613-4: 18×4.4, 10PR, 210 mph, nose gear
- Michelin 031-613-8: 18×4.4, 10PR, 210 mph, nose gear
- Michelin Air 027-613-0: 18×4.4, 10PR, 210 mph, nose gear
Frequently Asked Questions: Learjet 23
Is the Learjet 23 still in production?
No. Production ended in 1966 after 101 airframes, and the Model 24 replaced it. Tires and wheels remain readily available because the 23 shares its sizes with the Learjet 24, 25 and later 20-series aircraft that are still flying.
What are the Learjet 23 specifications?
Two General Electric CJ610-4 turbojets of 2,850 lbf each, a 12,499 lb maximum takeoff weight, 450 kt cruise, a 45,000ft ceiling and 6,900 ft/min of climb. Seating is two crew and six passengers. The full table above covers dimensions and field performance.
What is the range of the Learjet 23?
Approximately 1,591nm, or 1,830 statute miles, at maximum fuel. That is transcontinental in theory and more realistically a long single leg with reserves. The tip tanks are integral to the figure.
What is the Learjet 23 price?
There is no functioning used market. Only one airworthy example exists, and it trades as a collector aircraft at auction rather than on the business jet market. Museum-condition airframes change hands occasionally as static display pieces.
What does the Learjet 23 cost to operate per hour?
No current benchmark is meaningful. A first-generation CJ610 turbojet burns heavily by modern standards, and Stage 3 hush kit compliance, parts scarcity and specialist maintenance dominate the cost picture rather than fuel alone.
Where can I find a Learjet 23 for sale?
Listings are rare enough to be newsworthy. The one airworthy example has appeared at collector auction, and non-flying airframes turn up occasionally through salvage and museum channels. Mainstream business jet brokers do not carry the type.
Why were most Learjet 23s grounded?
US Stage 2 noise rules. The CJ610 turbojet cannot meet current limits without a hush kit, and the retrofit generally cost more than the airframe was worth. By 1998 only 39 aircraft were still operational, and attrition has run steadily since.
What interior does the Learjet 23 offer?
A six-seat cabin in a fuselage cross-section that is famously tight by modern standards, with a low ceiling and a club or side-facing arrangement depending on how the aircraft was completed. Cabin fit varied considerably between individual deliveries, since most were specified by the first owner.
What is the Learjet 23 landing distance?
Around 3,310ft, against a takeoff distance of 3,393ft. Approach speeds are high for the weight because the wing carries no leading edge devices, and a drag chute was fitted as standard equipment to help with the rollout.
What tire size does the Learjet 23 use?
The main gear takes 18×5.5 10-ply tubeless tires and the nose takes an 18×4.4 10-ply tubeless deflector tire. Both positions are typically rated to 210 mph. Verify the size and the deflector configuration against the maintenance manual and parts catalog for your serial number.
Which tire brands are approved for the Learjet 23?
Goodyear and Michelin both produce tires in the correct sizes and ratings. Goodyear covers the mains with the Flight Eagle 185F03-5 and Flight Leader 185K03-1, and the nose with the Flight Eagle DT 184F03-2 and Rib DDT 184F10-2. Michelin cross-references at both positions.
How much do Learjet 23 tires cost?
Business jet tires in these sizes sit well above light aircraft pricing, and the main and nose positions are broadly comparable to each other. Current pricing appears on the product listings linked in the brands section above.
What is the tire pressure for the Learjet 23?
Inflation pressures are published in the aircraft maintenance manual and should be checked cold. Tubeless tires at business jet pressures lose pressure slowly and continuously, so a daily check is standard practice rather than a precaution.
How long do Learjet 23 tires last?
Main gear tires on light jets of this weight typically give somewhere in the low hundreds of landings, and the 23 is harder on them than most because of its approach speed and limited braking. Nose tires generally outlast mains. Standing time matters more than hours on an aircraft that flies rarely.
How often should Learjet 23 tires be changed?
Replace at the tread wear limit, or earlier for cuts, bulges, flat spots, sidewall cracking or exposed cord. Flat spotting from long periods parked is the realistic driver on this type. A licensed engineer and the maintenance manual govern the final call.
