Learjet 55 / 55B / 55C — Primary-Source Technical Documentation Collection

The Learjet 55 "Longhorn" — Gates Learjet's definitive wide-cabin business jet — represented a structural and aerodynamic evolution of the classic Learjet formula. Powered by twin rear-mounted Honeywell TFE731-3A-2B turbofans and distinguished by its signature winglets (the origin of the "Longhorn" name), the Model 55 series was engineered for high-subsonic cruise efficiency, high-altitude stability, and extended range operations.

This archival collection assembles the primary-source technical library for the Learjet 55, 55B, and 55C variants — covering maintenance, wiring, structural repair, illustrated parts, and spare parts pricing across the full production run from aircraft 55-003 through the final 55C series.

Aircraft & Engineering Context

The Learjet 55 introduced a low-wing cantilever airframe with winglets designed to reduce induced drag at cruise altitudes. The 55C variant added dual lower-fuselage Delta Fins (strakes) that dramatically improved directional stability, eliminating the dual-yaw-damper dispatch requirement of earlier variants and reducing the system to a single passenger-comfort damper.

Boundary Layer Enhancement (BLE) on the 55C wing leading edges — raised exposed screws acting as micro-vortex generators — addressed low-speed stall characteristics identified during wind tunnel and flight testing. At high-subsonic cruise, boundary layer integrity is critical; distortions or inoperative control dampening can require reduction of M(MO) to 0.74 Mach.

Engine bleed air (HP and LP circuits) is regulated via a dedicated Bleed Air Mix Valve supplying cabin pressurization, wing leading-edge anti-ice, and nacelle/stator thermal coverage. Standard TFE731-3 engines operate on a 1,400-hour Major Periodic Inspection (MPI) cycle and a 4,200-hour Compressor Zone Inspection (CZI) cycle, with Honeywell-authorized overruns of 100 hours (MPI) and 200 hours (CZI).

Key Service Bulletins governing the fleet include SB 55-71-5 (engine replacement criteria for TFE731-3AR-3B/-3B1 upgrade) and SB 76-3067-3 (N1 DEEC digital engine control installation, wiring harness conversion, and Pt2/Ps0 pneumatic sensing integration).

Standard Baseline Performance

Document Manifest — What's Included

1. Learjet 55 Maintenance Manual

Manufacturer: Gates Learjet / Bombardier Aerospace
Reference: MM-101 | Original issue: March 6, 1981 | Revision 58, dated January 17, 2005
Coverage: Learjet 55, 55B, and 55C — full airframe systems, powerplant, avionics, hydraulics, flight controls, pressurization, and scheduled maintenance procedures. The most heavily revised document in the series, with 58 revision cycles reflecting the full operational life of the fleet.

2. Learjet 55B/C Wiring Manual

Manufacturer: Gates Learjet / Bombardier Aerospace
Reference: WM-101A | Original issue: August 1986 | Revision 7, dated January 17, 2005
Coverage: Aircraft 55-127 and subsequent (55B/C production block). Electrical schematics, wire routing, connector identification, and system circuit diagrams for the B/C variants.

3. Learjet 55 Wiring Manual

Manufacturer: Gates Learjet
Reference: WM-101 | Original issue: March 1981 | Revision 19, dated January 17, 2005
Coverage: Aircraft 55-003 through 55-126 (original production block). Electrical schematics and wiring diagrams for the baseline Learjet 55 series.

4. Learjet 55 Series Illustrated Parts Catalog

Manufacturer: Bombardier Aerospace
Reference: IPB-101 | Dated: July 14, 2000
Coverage: Supersedes the January 4, 1993 edition. Full illustrated parts breakdown for the Learjet 55 series — figure and item numbers, part numbers, effectivity codes, and unit-of-measure data across all major assemblies and sub-assemblies.

5. Learjet 55 Structural Repair Manual

Manufacturer: Gates Learjet Corporation
Reference: SRM-3 | Dated: May 1986
Coverage: Approved structural repair data for the Learjet 55 airframe — damage classification, repair limits, material specifications, and approved repair schemes for primary and secondary structure.

6. Bombardier Aerospace Spare Parts Price Catalog — Learjet Model Aircraft

Manufacturer: Bombardier Aerospace Business Aircraft Customer Support
Reference: Spare Parts Price Catalog | Dated: April 2004
Coverage: Spare parts pricing for Learjet models 23, 24, 25, 28, 31, 35, 36, 40, 45, 55, and 60. Includes the Learjet 55 series parts pricing as issued by Bombardier Customer Support.

⚠️ 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.

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.
Living Collections with Free Lifetime Updates — Please review our Disclaimer and Export Notice before purchasing.