Adam A500

The Adam A500 is a six-seat, twin-piston, centerline-thrust composite aircraft designed by Burt Rutan's Scaled Composites (as the Model 309 proof-of-concept) and brought to certification by Adam Aircraft Industries of Centennial, Colorado. It received FAA type certification in May 2005 under TC A00006DE. The A500 is notable for its pod-and-boom layout: a central fuselage with tractor and pusher Continental TSIO-550-E engines on the centerline, twin tail booms, and a connecting horizontal stabilizer — a modernized take on the Cessna 337 Skymaster concept executed in carbon-fiber composite.

Adam Aircraft promised the safety of twin-engine redundancy without the Vmc roll-off of conventional twins, plus jet-like cabin comfort in a piston package. It never delivered on its business case. Adam Aircraft ceased operations on 11 February 2008 and filed Chapter 7 on 19 February 2008, having delivered only seven airframes (s/n 0001–0007). The company burned through roughly $300 million of investor capital pursuing the A500 and its A700 very light jet derivative. Today the A500 is the textbook definition of an orphan aircraft: a tiny fleet, no factory, essentially zero parts supply, and a type certificate that has changed hands among receivers with no meaningful support.

It is included in this wiki as a cautionary data point and for completeness. No rational buyer should consider an A500 for any mission where regular dispatch reliability matters. See maintenance-ecosystem for the economics of orphan support.

Related but separate: the Adam A700 AdamJet was a jet derivative of the A500 airframe concept that never achieved certification before the bankruptcy.

Book cruise is approximately 220 KTAS at mid-teens altitudes with combined fuel burn near 38 gph (roughly 19 gph per engine at a 195-kt low-cruise setting per flight test reports). Service ceiling is 25,000 ft all-engines, but single-engine service ceiling is only about 14,900 ft — respectable for a piston twin but a reminder that centerline thrust does not eliminate the performance penalty of losing an engine.

The most famous real-world performance issue is payload. The original marketing promised roughly 720 lb of payload with full fuel; the production airframe (s/n 7) came in 1,150 lb heavier than brochure empty weight. With the 230-gallon tanks full, only about 160 lb of crew/passenger/baggage payload remained — insufficient for a single adult pilot at standard weights. Operators routinely flew with partial fuel, cutting practical range well below the 892 nm book number.

Centerline thrust does deliver its promised handling benefit: engine-out asymmetry is near zero, Vmc is effectively a non-issue, and the aircraft does not demand the rudder discipline of a conventional light twin.

The A500's payload-range chart is its worst feature. With 230 gallons of avgas (approximately 1,380 lb of fuel), useful load of roughly 1,650 lb leaves only ~270 lb for crew, passengers, and baggage — and on the heavier production serial numbers, closer to 160 lb. That does not cover a single pilot and a flight bag.

Practical scenarios:

• Full fuel (230 gal), solo pilot: Barely legal on the heaviest s/n; ~900 nm range.
• Four adults (680 lb), full baggage (100 lb): Requires leaving roughly 870 lb of fuel behind, i.e. about 85 gallons loaded versus 230 gallons capacity. Range collapses to roughly 250–300 nm.
• Six adults (1,020 lb): Not practically possible; the airplane seats six but cannot carry them with meaningful fuel.

For context, the cessna-337-skymaster — the conceptual ancestor — offers a similar centerline-thrust layout with dramatically better economics, real parts support, and similar practical payload-range despite being fifty years older. A buyer attracted to centerline-thrust twins should start and end at the Skymaster.

• Flight training (1/10): Disqualified. Orphan parts, cost, complexity, and negligible fleet.
• Backcountry (1/10): Disqualified. Low-wing composite twin with retractable gear; wrong airplane entirely.
• Business travel (3/10): The design intent was exactly this — pressurized-feel cabin, 220-kt cruise, twin redundancy. Execution fails on dispatch reliability due to parts. If you could keep it flying, the mission fits. You cannot keep it flying.
• Aerobatics (1/10): Not certified or suitable.
• Cross-country (cross-country, 4/10): Would earn a 7 on speed and range alone, penalized heavily for AOG risk and payload limits.
• Cargo hauling (2/10): Payload math is fatal.
• Local fun (2/10): No. The hourly cost and maintenance exposure eliminate casual use.
• Surveying (2/10): Twin redundancy and high cruise would be appealing; orphan status disqualifies.

Factory panels were Avidyne Entegra integrated flight decks (PFD + MFD) with dual Garmin GNS 430/530 navigators, S-TEC or Avidyne-integrated autopilot, and Ryan TCAD/traffic. The cabin is pressurized-looking but not pressurized. Upgrading the factory Entegra is possible in principle (Garmin G500 TXi or similar) but non-trivial in a composite low-production airframe without STC precedent — every install is effectively a field approval exercise.

ADS-B Out compliance for surviving airframes was handled case-by-case, typically via GTX 345 or similar transponder swap tied to the existing Garmin GPS sources.

Essentially none. Because the fleet is seven airframes, there is no economic basis for third-party STC development. Any modification is a one-off field approval, and the absence of the type certificate holder as a going concern makes engineering data nearly impossible to obtain. This is a closed ecosystem.

See maintenance-ecosystem. This is the defining weakness of the A500:

• Parts availability: poor — Effectively zero factory parts pipeline. The A500 Owners Association has served as the informal clearinghouse, with owners swapping, fabricating, and cannibalizing parts.
• Mechanic familiarity: rare — Fewer than a dozen A&Ps worldwide have meaningful A500 experience. Composite repair requires specialists; low-production composite structures are particularly unforgiving.
• Annual cost estimate: $60,000+ — This is a rough placeholder; a single squawk that requires an unobtainable part can turn an annual into a multi-year AOG event.
• Engines and accessories: These are standard Continental TSIO-550-E and support well through Continental Motors and field overhaul shops.
• Airframe-specific items: Landing gear, pressurization-style door seals, cowling hardware, cabin components — all orphaned.

See valuation-methodology. Standard methodology largely breaks down on orphan airframes. Observed asking prices over the past decade have ranged from roughly $250,000 to $500,000 depending on engine time and avionics, compared to the 2007 list price of $1.3 million. The aircraft does not have a real bluebook — Vref and Aircraft Bluebook either omit it or list it as "insufficient data."

Price drivers (such as they are):

• Engine times: Run-out TSIO-550s are the single biggest variable. A fresh overhaul adds roughly $90,000 per engine.
• Airworthiness status: Several surviving airframes have been non-flying for years. A currently-flying, annualled A500 commands a significant premium over a hangar queen because returning one to service requires sourcing parts that essentially do not exist.
• Avionics currency: ADS-B compliance and a healthy Entegra are non-trivial; a dead PFD can ground the airplane indefinitely.
• Documentation: Logs and any factory engineering data that the owner can produce have outsized value because they cannot be replaced.

Realistically, the A500 is worth whatever a well-capitalized enthusiast will pay, which is closer to the scrap value of the engines and avionics than to any cost-approach valuation of the airframe.

The A500 has relatively few active airworthiness directives purely because the fleet is too small to generate meaningful service history. Known issue patterns from the A500 Owners Association and press coverage include:

• Parts unobtainium: The dominant "problem." Composite structural repair parts, landing gear components, and airframe-specific hardware have no supplier. At least one airframe was reported grounded in August 2008 due to inability to source parts, and AAI Acquisitions (the post-bankruptcy TC holder) publicly stated "there's no economic model that justifies setting up a support team to support just five planes in the field."
• Engine ADs: The TSIO-550-E is subject to standard Continental ADs (crankshaft, cylinder, magneto) that apply fleet-wide regardless of airframe. Engine support is fine; airframe support is not.
• Weight creep: Not an AD, but a documented design issue — production airframes were well over brochure empty weight.
• Pressurization: Note that despite the jet-like fuselage appearance, the A500 is unpressurized. Do not confuse it with the A700 jet.

See insurance-underwriting. Orphan twins of this category fall outside standard carrier appetite. The handful of insurers willing to quote treat the A500 as a bespoke risk. Expected annual hull premiums run in the $15,000–$25,000 range on a $350,000 hull, with liability often carrying low sub-limits per passenger. Underwriters typically require:

• ATP or commercial with significant multi-engine time
• Formal transition training (essentially impossible to obtain — no factory school exists, so carriers accept mentored time with an experienced A500 pilot, of whom there are a single-digit number in the world)
• Annual recurrent
• Declared basing and hangar

Hull values above $400,000 are generally rejected. A total loss is effectively a total loss; there is no repair path.