Learjet 28/29 Longhorn — Primary-Source Technical Documentation Archive

The Learjet 28 and Learjet 29 — collectively marketed as the Learjet Longhorn series — hold a unique and permanent place in aviation history as the first commercial aircraft in the world to fly with winglets. Manufactured between 1977 and 1982 in extremely limited numbers (five Learjet 28s and four Learjet 29s), these aircraft were built on the proven Learjet 25 airframe but transformed by NASA-derived supercritical winglets that replaced the traditional wingtip fuel tanks. The result was a certified operational ceiling of 51,000 feet (FL510) — the highest of any business jet of its era — and a cruise L/D ratio optimized for ultra-high-altitude efficiency that no contemporary could match. Because of the tiny combined fleet of just nine aircraft, engineering documentation for the 28 and 29 is consolidated into unified fleet manuals, making this collection exceptionally rare. This archive assembles the complete primary-source factory documentation for the entire Learjet Longhorn series.

What's Included — Document Manifest

1. Learjet 28/29 Maintenance Manual (MM-100)
Published: December 1, 1978 · Revision No. 32, dated May 30, 2005
The definitive factory maintenance manual for the entire Learjet 28/29 Longhorn fleet. Covers all systems, winglet integration, fuel system management (including the Learjet 29's enlarged fuselage tank adding 1,000 lbs of fuel capacity to compensate for the deleted wingtip tanks), CJ610-8A engine servicing, dual yaw damper system, and Phase A–D inspection intervals. Includes compliance data for structural bulletins such as SB 28/29-27 (flap roller rib and track roller fitting NDT inspections).

2. Learjet All 28/29 Models Illustrated Parts Catalog (IPB-100)
Gates Learjet Corporation · Original Issue, December 1, 1978
Full illustrated breakdown of all Learjet 28/29 airframe assemblies, sub-assemblies, and line-replaceable units. Covers both the Learjet 28 (winglets, no fuselage tank) and Learjet 29 (winglets, enlarged fuselage tank) configurations. Essential for parts identification, sourcing, and restoration of these extraordinarily rare airframes.

3. Learjet 28/29 Wiring Manual (WM-100)
Published: December 1, 1978 · Revision No. 7, dated May 30, 2005
Factory wiring manual covering the complete electrical system architecture for the Learjet 28/29 series. Includes all circuit diagrams, wire routing, connector data, and avionics integration schematics for both variants.

4. Learjet 20/30 Series Structural Repair Manual (SRM-4)
Published: May 15, 1992 · Revised: July 10, 1998 (Rev. No. 4)
Structural repair data, allowable damage limits, and repair procedures for the Learjet 20 and 30 series family — the direct structural lineage of the Learjet 28/29. Addresses primary spar caps, wing attachments, and fuselage skin fatigue zones. Critical reference for the modified wing root geometry introduced by the winglet installation.

5. Learjet 28/29 Service Bulletins, Service Newsletters & ADs
Bombardier Aerospace · Covers the complete Longhorn fleet
A comprehensive compilation of Service Bulletins (SB), Service Newsletters, Special Spares Kits, Airplane Modification Kits, Field Change Notices, Service Information Letters, Advisory Bulletins/Wires, and Airworthiness Directives (ADs). Includes critical structural alert bulletins such as SB 28/29-27 (non-destructive testing of inboard/outboard flap roller ribs and track roller fittings) and fuel system bulletins regulating approved fuel grades (ASTM D1655 Jet A/A-1) at extreme high-altitude temperatures.

6. Bombardier Aerospace — Learjet Spare Parts Price Catalog
Published: April 2004 · Covers Learjet Models 23, 24, 25, 28, 31, 35, 36, 40, 45, 55 & 60
Bombardier Customer Support official spare parts pricing reference. Invaluable for restoration budgeting, parts valuation research, and historical cost documentation across the full Learjet family including the rare Longhorn series.

Aircraft Technical Profile

Winglet Innovation
The Learjet 29 introduced NASA-derived supercritical winglets — the first on any commercial aircraft — replacing the traditional wingtip fuel tanks of the Learjet 25. By diffusing wingtip vortices, the winglets dramatically reduced induced drag and minimized total parasite drag, enabling FL510 operations. The Learjet 28 retained the winglets but without the enlarged fuselage fuel tank of the 29.

Powerplant
Twin General Electric CJ610-8A single-rotor turbojets · 2,950 lbf per engine · rear fuselage mounted. Maximum continuous ITT and RPM restricted by technical bulletins to prevent thermal fatigue at high-altitude thin-air operations. Learjet 29 fuselage tank adds 1,000 lbs fuel capacity over the Learjet 28.

Handling & Stability
Winglet installation required re-evaluation of pitch and roll stability boundaries due to altered spanwise lift distribution. Dual yaw damper configuration manages Dutch roll susceptibility at high Mach numbers. At FL510, the aircraft operates at the "coffin corner" — the narrow margin between aerodynamic stall and Mach buffet — demanding precise pilot management.

Performance Data

This is an archival, static-copy edition fixed at its original publication date. Intended for historical reference, flight simulation, museum restoration, and educational use only. Not approved for active airworthiness maintenance under FAA 14 CFR § 43.13, EASA Part-M, or equivalent international regulations. Operators of active aircraft must use current, revision-controlled publications from the Type Certificate holder or an authorized distributor.

⚠️ Regulatory Notice: Under FAA 14 CFR § 43.13 and EASA Part-M, any mechanic performing maintenance on an active aircraft must use current, manufacturer-approved revision-controlled data. This archival document does not satisfy that requirement.

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