PZL-104 Wilga

The PZL-104 Wilga ("Oriole" in Polish) is a Polish high-wing STOL utility aircraft designed by PZL Warszawa-Okecie, with the prototype first flying on 24 April 1962. Over 1,000 airframes were built across roughly four decades of production (around 935 to Wilga 35/80 standards plus later Wilga 2000 variants), making it one of the most-produced Polish aircraft ever. Production ended in 2006 under EADS ownership.

The Wilga has an unmistakable appearance: a deep-chord high wing with full-span leading-edge slats and slotted flaps, a long-legged conventional gear with a trailing-link suspension that absorbs outrageous arrivals, massively upswept outer wing tips, and a greenhouse cabin with enormous convex doors that the glider tow community loves for visibility on the rope. In US service, the Wilga is almost exclusively a glider tug — its combination of 260 hp, low stall speed, enormous flaps, and a pre-installed Tost tow hook makes it a natural replacement for tired Pawnees and L-19 Bird Dogs at soaring clubs.

The airplane has a devoted but small following. Owners love its STOL performance, Cold War tank-like build quality, and the theater of the AI-14R radial's cough-and-roar startup. Detractors cite the maintenance nightmare: Soviet-era radial engines with 800-hour TBO, calendar-time airframe limits, sparse parts, and a rapidly vanishing pool of mechanics who know how to touch it. See maintenance-ecosystem for context on how orphan-support aircraft fare long-term.

The Wilga 80 is the dominant variant in US registries because it was the only one certified under FAR 23 for American import. A minority of US Wilgas are Wilga 35s operating on Experimental Exhibition or grandfathered certificates, and a small number of Wilga 2000s with Lycoming engines exist at higher price points.

Published "cruise speeds" for the Wilga need to be interpreted carefully. PZL brochures quote around 195 km/h (105 KTAS) as max level speed, but the aircraft is draggy enough that a realistic block cruise at 65% power is closer to 85–90 KTAS burning 13–14 GPH of avgas — roughly Cessna 172 speed with twice the fuel burn. The airplane is not a cross-country machine.

Where the Wilga shines is at the slow end of the envelope. Full-span leading-edge slats deploy automatically around 50 KIAS and, combined with 44-degree Fowler-style flaps, produce a stall around 32 KIAS in landing configuration. Ground roll at gross is under 400 ft on pavement and even shorter on grass. Climb at light weights exceeds 1,300 fpm, which is why it is such a capable glider tug — a Wilga pulling a heavy two-seat glider off grass at density altitude will routinely outclimb a Pawnee 235.

Density altitude degrades performance noticeably above 5,000 ft because the AI-14R is a non-supercharged radial, but the airframe compensates: even with a 20% performance hit, the Wilga will still operate out of strips where nosewheel trainers would be trapped.

With 44 gallons of usable fuel (264 lb) and 801 lb useful load:

• Full fuel (264 lb), 2 pax + bags: Pilot and passenger at 180 lb each = 360 lb, leaving ~177 lb for baggage. Comfortable four-hour leg at 88 KTAS covers ~300 nm with reserves. Most practical touring loadout.
• Full 4 seats (720 lb), reduced fuel: 801 − 720 = 81 lb fuel ≈ 13 gallons, or roughly 45 minutes of flight. Effectively a pattern-only loadout with four adults; the Wilga is not a realistic four-place traveling airplane.
• 3 pax + bags (540 lb), useful fuel: 261 lb ≈ 43 gallons. Effectively full fuel. Three adults plus 120 lb of gear is a realistic three-hour, ~250 nm mission.
• Glider tow loadout: Pilot + 30 gal fuel (180 lb) = 360 lb used, leaving 440 lb for tow-line loads, water ballast effects, and margin. A Wilga at this loading is an excellent tug on grass.

The Wilga is best understood as a two-to-three-place STOL utility aircraft with a fourth seat for kids or short hops — not a four-up cross-country machine.

Backcountry / Bush (8/10): Strong. Short-field performance, oversized trailing-link gear that swallows rough strips, four seats, and a cargo-friendly cabin make it a capable bush machine. Lower score than a Husky or Super Cub only because of maintenance logistics and parts scarcity that make it risky far from support. See backcountry-bush.

Local Fun Flying (8/10): This is where most US Wilgas live — weekend stick-and-rudder airplane with character, head-turning ramp presence, and a radial soundtrack. Perfect for pilots who want something unusual at a grass-strip home base.

Surveying / Observation (6/10): The greenhouse doors and slow flight envelope are excellent for photo work, pipeline patrol, and wildlife observation. Held back by fuel burn and endurance relative to a 182 or 206.

Cargo Hauling (5/10): Useful load is honest (~800 lb) and the cabin is boxy, but payload-range is limited by the thirsty radial. Good for local utility hops, poor for anything long.

Flight Training (3/10): Tailwheel, radial, and slat-equipped — a fantastic transition aircraft but wholly unsuitable as a primary trainer due to complexity, cost, and insurance. A few schools use Wilgas for tailwheel endorsements.

Cross-Country (2/10): 88-KTAS cruise + 13.5 GPH = a painful combination. Range with reserves is barely 300 nm. You can do it; you won't enjoy it. See local-fun-flying.

Aerobatics (2/10): Not certified for aerobatics, though the airframe is stressed for mild sport work. Utility category only.

Business Travel (1/10): No.

Wilga 80s delivered to the US typically came with minimalist VFR panels: KX 155 NAV/COM, transponder, and basic engine gauges. Many were delivered with Polish instruments (in metric units) that were swapped for US-standard instruments during import. IFR-capable panels are rare and the airplane is not commonly flown IFR in US service due to limited avionics space, no autopilot provision, and the operational role (VFR glider towing and local flying).

Typical US panel configurations:

• Stock tow-plane (~$3–8k panel): Single VHF, Mode C transponder, handheld GPS, CHT/EGT. Sufficient for a club tug.
• Upgraded VFR (~$15–25k): Garmin GTR 225 or GTN 650, GTX 345 ADS-B transponder, Garmin G5 attitude indicator, Aera 760 or iPad panel mount.
• Wilga 2000 glass (factory): Some Wilga 2000 airframes were delivered with Bendix/King or early Garmin integrated panels; rare and expensive.

See avionics-pricing for install cost benchmarks.

The Wilga fleet is small enough that the STC ecosystem is thin. Notable modifications seen in US service:

• Lycoming IO-540 conversion: A few owners have undertaken engine swaps replacing the AI-14R with a Lycoming IO-540 (the Wilga 2000 engine) on a field approval or one-off basis. Adds $80–120k to the project, improves reliability and parts support dramatically, and changes the character of the airplane (no more radial sound). Discussed extensively on backcountry-pilot forums.
• M-14P upgrade: Some owners have swapped in the Yak-18T/Su-26 Vedeneyev M-14P 360 hp radial. This improves TBO and parts support (M-14P is used in the Yak and Sukhoi fleet, so US support is better than AI-14R), and adds 100 hp. Field-approval territory.
• Tost glider tow hook: Standard on most US Wilgas; factory provision makes installation simple.
• Oil cooler upgrades: Common to address AI-14R running-hot issues in US climates.
• Skis and floats: Factory-supported; rare in the US, more common in Polish/Scandinavian service.

This is the Wilga's biggest weakness and the single most important factor in an ownership decision.

• AI-14R TBO: 800 hours nominally. Western oils and careful operation let US operators routinely exceed this, but the engine is aging calendar-wise regardless.
• Overhaul cost: $35,000–$55,000 when possible, at one of a handful of shops with AI-14 capability. Lead times can run 6–12 months. Some owners report quotes over $60k.
• Parts availability: Poor. No new-production AI-14R parts are made. NOS (new old stock) from Poland, Russia, Ukraine, and occasionally Cuba is hoarded by individual owners and brokers. Common consumables (spark plugs, gaskets, filters) are obtainable; expensive items (cylinders, crankshafts, magnetos) are elusive and expensive.
• Mechanic familiarity: Rare. A&P/IAs willing to work on an AI-14R are vanishingly few. Some Yak-52 mechanics will touch the AI-14 because of their M-14P expertise. Airframe work is more approachable because the structure is conventional aluminum.
• Annual inspection cost: Typically $3,500–$8,000 if nothing is wrong, which is rare. Realistic total annual ownership cost (insurance + hangar + annual + reserves) runs $18,000–$28,000 before a single drop of fuel.
• Airframe parts: PZL Mielec (now under Sikorsky/Lockheed) does not actively support the Wilga. Some parts are available through Polish aero clubs; fabricating minor items on field approval is common.

The Lycoming-converted Wilgas sidestep most of these issues and are, from a pure ownership-cost standpoint, the rational choice — at the cost of the radial soundtrack that made you want a Wilga in the first place.

Wilga pricing in the US is bimodal and highly condition-dependent. See valuation-methodology for general framework.

• Project / high-time AI-14R Wilga 35: $40,000–$70,000. Runnable but with a looming engine problem.
• Solid Wilga 80 with mid-time AI-14R: $90,000–$140,000. The core of the market; most US-registered tow planes fall here.
• Low-time or freshly overhauled Wilga 80: $140,000–$180,000. Rare because overhauls are expensive and often triggered only at sale.
• Lycoming-converted Wilga 35/80: $160,000–$220,000. Premium reflects the engine upgrade's practical value.
• Wilga 2000 (factory Lycoming): $180,000–$260,000. Scarce in the US market; the sweet spot for a buyer who wants the Wilga character without the Soviet-radial headache.

Price drivers, in order: engine status (hours since overhaul and documented parts source), airframe life-limit status, avionics (minor), US paint and documentation history (whether it's a legit FAR 23 import or a gray-market airframe). Glider clubs buying specifically as a tug will pay a premium for known history and a working Tost hook.

The US Wilga fleet is small, so AD activity is limited, but the following are known concerns:

• AI-14R cylinder cracking: Individual cylinders crack at the head-to-barrel junction. Replacement cylinders are NOS-only and prices have tripled since 2015.
• Magneto drive issues: The Soviet magnetos are wear items with limited parts; many owners convert to Slick or Bendix magnetos where possible.
• Airframe calendar life: PZL originally specified calendar-time limits on the airframe (lifetime around 6,000 hours or 20-30 years for some components). Polish CAA has extended these with inspections; FAA operators must work with their DER on life-extension programs.
• Wing attach fittings: Inspection required per PZL service bulletins; corrosion concerns in salt-air environments.
• Fuel tank sealing: Older airframes have experienced tank weepage; resealing is expensive due to cabin structure.
• Slat mechanism wear: Leading-edge slat tracks must be inspected for wear and corrosion — a compromised slat will cause asymmetric stall.

Pre-buy red flags: airframe hours near any published life limit, AI-14R with high time since overhaul and no documented parts source, missing PZL service bulletin compliance, and corrosion in the lower fuselage longerons.

See insurance-underwriting for category context. Wilga insurance is firmly in specialty-import taildragger territory:

• Hull premium: Typically 2.5–4% of insured value annually. A $120,000 Wilga 80 is around $3,000–$4,500/year hull plus $500–$800 liability.
• Underwriting: A small number of underwriters will quote the Wilga at all. Global Aerospace, Starr, and Avemco have historically been accessible; some markets will not write it.
• Pilot requirements: Typical minimums are PPL + 250–500 TT + 50–100 tailwheel + 10 hours dual in type. Some carriers require a named-pilot policy. Low-time pilots will struggle to get insured.
• Glider-tow endorsement: Must be declared; some policies exclude commercial tow operations, so club use requires a dedicated commercial policy (~50% premium uplift).
• Parts-availability surcharge: Some underwriters add a loading because a modest prop strike or ground loop can become a total loss given the cost and difficulty of sourcing parts.