Learjet 25 — Primary-Source Technical Documentation Archive
The Learjet 25 is the stretched-fuselage evolution of the Learjet 24, certified under FAR Part 25 airworthiness standards and produced across multiple sub-variants — the 25, 25B, 25C, 25D, and 25F — spanning production from 1967 through the early 1980s. Powered by twin rear-mounted General Electric CJ610-6 or CJ610-8A turbojets delivering 2,850 lbf per engine, the Learjet 25 pushed range and payload further while retaining the razor-sharp handling of its predecessors. The Century III wing modification on the 25D re-contoured the leading edge, dramatically improving high-altitude cruise efficiency, reducing stall vulnerability, and shortening landing runway requirements. Celebrated as a true pilot's airplane, the Learjet 25 also served as the platform for the Calspan Variable Stability System (VSS) research aircraft — one of the most important flight dynamics research tools in aviation history. This collection assembles the most comprehensive primary-source factory documentation available for the entire Learjet 25 family.
What's Included — Document Manifest
1. Learjet 25 Service Manual (SM-95)
Published: May 1969 · Last change: February 14, 2005
The original factory service manual for the Learjet 25 series. Covers all systems, rigging, servicing procedures, spoiler deployment rules, fuel imbalance limits (600 lbs cross-feed / 800 lbs wingtip landing), and CJ610 engine integration. Includes stall warning stick-shaker and dual yaw damper system requirements.
2. Learjet 25 Series Illustrated Parts Catalog (IPB-95)
Published: October 22, 1999 · Revision 1 dated August 9, 2000
Full illustrated breakdown of all Learjet 25 series airframe assemblies, sub-assemblies, and line-replaceable units. Essential for parts identification, sourcing, and restoration across the complete 25 family production run.
3. Learjet 25B/C/D/F Maintenance Manual (MM-98)
Published: December 2, 1977 · Revision No. 45, February 14, 2005
The definitive factory maintenance manual for the late-model 25B, 25C, 25D, and 25F variants. Covers Phase A–D inspection intervals (300 / 600 / 1,200 / 2,400 flight hours), structural alert compliance, and Gates Learjet Door Modification Kit AMK 78-2 integration terminating recurring AD 77-19-02 inspection requirements.
4. Learjet 25B/C/D/F Wiring Manual (WM-98)
Published: December 2, 1977 · Revision No. 10, February 14, 2005
Factory wiring manual covering the complete electrical system architecture for the 25B/C/D/F variants. Includes all circuit diagrams, wire routing, connector data, and avionics integration schematics.
5. Learjet 25B/C/D/F — Service Bulletins, Service Newsletters & ADs
Bombardier Aerospace · Covers Learjet 23/24/25 series
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 AD 77-19-02 (main entryway support pins and structural retention bolt fatigue inspection).
6. 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 shared by the Learjet 25. Addresses primary spar caps, wing attachments, and fuselage skin fatigue zones.
7. Learjet Mark II Service Manual
Gates Learjet Corporation
Factory service manual for the Learjet Mark II variant — the transitional designation bridging the early 25 series toward the refined Century III configuration. A rare and historically significant document covering the intermediate production block.
8. Learjet Mark II Illustrated Parts Catalog
Gates Learjet Corporation
Illustrated parts breakdown for the Learjet Mark II variant. Complements the Mark II Service Manual for complete parts identification and sourcing coverage of this transitional production series.
9. Learjet 24/25 Series — Dimensions, Areas, Structures & Doors
Factory reference document covering airframe dimensional data, structural area definitions, and door geometry for the Learjet 24 and 25 series. Includes front-view and side-view engineering line drawings.
10. 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.
Aircraft Technical Profile
Aerodynamics & Wing
Stretched fuselage development of the Learjet 24. Low-aspect-ratio straight wing with fixed wingtip fuel tanks and T-tail assembly. Physical spoilers for roll assistance and aerodynamic braking — prohibited with flaps extended and restricted past Vmo/Mmo. Century III mod (25D): re-contoured/re-cambered leading edge improving cruise efficiency, stall margins, and landing field length.
Powerplant
Twin General Electric CJ610-6 / CJ610-8A rear pylon-mounted turbojets · 2,850 lbf (13.1 kN) per engine · 5,700 lbf combined. Fuel burn baseline: Gross Weight × 0.1 (+500 lbs first hour). Max cross-feed imbalance: 600 lbs. Max wingtip tank landing imbalance: 800 lbs.
Handling & Stability
Calspan VSS research platform — one of aviation's most important flight dynamics research aircraft. Razor-sharp pitch sensitivity at rotation (120–138 KIAS) due to short elevator moment arm. Dual yaw dampers and stall warning stick-shaker mandatory for dispatch. Stitched quasi-LPV flight dynamics models developed across full envelope.
Performance Data
| Parameter | Value |
|---|---|
| Maximum Takeoff Weight (MTOW) | 15,000 lbs (6,804 kg) |
| Maximum Operating Altitude | FL450 (FL510 on 25D variants) |
| Normal Cruising Speed | 464 knots (545 mph) |
| Maximum Range | 1,500–1,830 nautical miles |
| Initial Rate of Climb (sea level) | 6,050–7,850 fpm |
| Balanced Takeoff Distance | ~3,937 ft (1,200 m) |
| Normal Landing Field | ~2,600 ft (836 m) |
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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