Lycoming T-55 Aircraft Engines Manuals Collection

A comprehensive digital collection of official U.S. Army technical manuals covering the Lycoming T-55 turboshaft engine — the powerplant of the legendary Boeing CH-47 Chinook heavy-lift helicopter. This collection spans the T-55-L-712 and T-55-L-714 variants and includes Aviation Unit and Intermediate Maintenance Repair Parts and Special Tools Lists.

Manuals Included

T-55-L-714 Series

• Aviation Unit and Intermediate Maintenance Repair Parts and Special Tools List — Turbine Aircraft Engines Model T-55-L-714 — TM-1-2840-252-23-1
• Aviation Unit and Intermediate Maintenance Repair Parts and Special Tools List — Turbine Aircraft Engines Model T-55-L-714 — TM-1-2840-252-23-2
• Aviation Unit and Intermediate Maintenance Repair Parts and Special Tools List — Turbine Aircraft Engines Model T-55-L-714 — TM-1-2840-252-23-3
• Aviation Unit and Intermediate Maintenance Repair Parts and Special Tools List — Turbine Aircraft Engines Model T-55-L-714 — TM-1-2840-252-23P

T-55-L-712 Series

• Aviation Unit and Intermediate Maintenance Repair Parts and Special Tools List — Turbine Aircraft Engines Model T-55-L-712 — TM55-2840-254-23-2
• Aviation Unit and Intermediate Maintenance Repair Parts and Special Tools List — Turbine Aircraft Engines Model T-55-L-712 — TM55-2840-254-23-3
• Aviation Unit and Intermediate Maintenance Repair Parts and Special Tools List — Turbine Aircraft Engines Model T-55-L-712 — TM55-2840-254-23-4
• Aviation Unit and Intermediate Maintenance Repair Parts and Special Tools List — Turbine Aircraft Engines Model T-55-L-712 — TM-1-2840-254-23P

About the Lycoming T-55 Engine

The Lycoming T-55 is a free-turbine turboshaft engine developed by the Lycoming Turbine Engine Division (Stratford, CT) — now Honeywell Aerospace. First run in 1955 and qualified for flight in 1961, it was designed as a scaled-up evolution of the Lycoming T53 and has powered heavy-lift rotorcraft in continuous military service for over six decades.

Primary aircraft applications include:

• Boeing CH-47 Chinook (all variants, including F/G models)
• MH-47E/G Special Operations
• Bell 309 KingCobra
• North American YAT-28E Trojan
• Curtiss-Wright X-19
• Bell 214A (civilian)

Technical Specifications

• Engine type: Turboshaft (free-turbine)
• Compressor: 7-stage axial-flow + 1-stage centrifugal-flow
• Turbine: 2-stage gas producer + 2-stage power turbine
• Power range: 1,600 shp (initial T55-L-5) to 5,000+ shp (T55-GA-714C)
• Compression ratio: ~9.32:1
• Weight: ~560 lbs (early) to ~830 lbs (later variants)
• Fuel: Jet A-1 / JP-4 / JP-8
• Notable features: Reverse flow combustor, split-shaft design, integral oil tank (later models)

Key Variants

• T55-L-5: 1,870 shp — 1961 production entry
• T55-L-7/L-7C: 2,850 shp
• T55-L-11A: 3,750 shp
• T55-L-714A/C: 5,000+ shp — improved reliability and fuel consumption

Operational History

The T-55 has been the backbone of U.S. Army heavy-lift helicopter operations since the Vietnam War, serving through the Gulf War and all subsequent major conflicts. Today, the engine remains in active military service powering CH-47F/G and MH-47G Chinooks, with continued modernization managed through the T55 Center of Excellence. The current Type Certificate holder is Honeywell Aerospace.

Format & Delivery

• Format: PDF (digital download)
• Delivery: Instant download after purchase
• Files: Delivered as a compressed archive (RAR/ZIP). You will need a free extraction tool such as 7-Zip (Windows), WinRAR (Windows), or The Unarchiver (Mac) to extract the files before opening the PDFs.

Export & Compliance Notice

These materials consist of historical U.S. military technical publications spanning 1941 to 1959 (TM series), provided for educational, research, and reference purposes only.

Each document has been reviewed for obvious restrictions and does not display classification markings, export control notices, or distribution limitations on the cover or within the document body.

The publications are sourced from publicly available repositories, including the Defense Technical Information Center (DTIC) and Internet Archive, and are offered in consolidated form for the convenience of researchers, historians, restorers, and aviation enthusiasts.

These materials are not intended for current operational, certification, or repair use, nor for the manufacture or modification of any aircraft or systems.

No ITAR-controlled or EAR-restricted material is knowingly included.

To the best of our knowledge, the materials do not contain currently classified information or content subject to active export restrictions. However, no representation or warranty is made regarding export classification status.

By completing this purchase, you agree to comply with all applicable laws and regulations, including any export or import requirements in your country.