T21D-at-Night-Small-Pole-Replaced-with-trees T he Celtech A/M37T-21D Mobile Turboprop Engine Test Stand is accepted for use by the USAF, USN, Allies, Fleets & MROs for testing all series of the T56, T38, 501D, and AE2100 turboprop engines.  Celtech is proud to produce the most widely used turboprop engine test stand in the world.  The T-21D is your convenient “prop on” test stand.  Thorough reviews of the T21 by Atec and Celtech since our 2013 merger have advanced many new improvements, while preserving compatibility and configuration.

Control-Cab-3As T21 worldwide repairs and support contractor to USAF, many technology refreshments for obsolete components and ECs can be provided during USAF repairs through Atec. Celtech customers are assured strengthened after sales support in spare parts and service from our new Atec resources. Commercial fleets and maintainers that are showing renewed interest in these engines and planes are also interested in T21 “prop on” testing. We offer service contracts to ensure your equipment is maintained properly and will work with your technical staff to answer any questions and provide technical support. Celtech’s products and services benefit from an impressive engine support ancestry involving Space Corp., Page Avjet, Knight Aero, Shaw & Estes, ASE and now, Atec. 






Control Trailer:




5000 lb

Run-Up Trailer 




15900 lb

Fuel Trailer (2500 gallons)




3750 lb

 Celtech offers a complete, mobile A/M37T-21 Engine Test System

Turboprop Trailer Assembly T-21J webThe run-up trailer is the main unit holding the engine under test, providing connection to all system components and an efficient work platform for test and repair personnel.  Ongoing technology refreshments during repairs, upgrades and options keep the Celtech T21D compatible for use with today’s more powerful propellers and engines.  This run-up trailer is the main engine test unit holding the tested engine and all systems connections.  The mobile trailer assembly provides a secure mounting base for the engine adapter kit, including a tie-down kit for securing to the base pad and breakaway interlock. The trailer design provides a mounting point for the fuel valve and electrical junction box. The trailer comes equipped with removable running gear/axles.

Control CabControl-CabThe climate-controlled, mobile control cab now hosts the advanced ADAQ™ control and software data acquisition system, including the renowned Atec throttle.  ADAQ™ allows finer control, broad data collection, trending, communications and flexible report generation. The obsolete aircraft gauges are now on screen digital displays, and torque is more precisely measured. A larger control cab is available as an option. Older ENDAS throttles and systems can often still be supported.

Fuel SystemT-21-Tuel-Tank_editThe mobile fuel system contains all components needed for engine testing, including pump, filter, and flow meter. The fuel system adheres to MS design and safety standards and is compatible with Air Force hardware. The standard fuel trailer capacity is 2500 gallons; options available.

Ancillary Equipment The start cart and generator set are Government Furnished Equipment (GFE) needed to test engines. Celtech manufactures accessories as options.

Control Kit  In addition to the items listed above, an engine specific test stand control kit is required. Test stand control kits include such items as dress equipment, cables, generator load bank, hydraulic service, etc. Celtech provides test stand control kits for a wide variety of engines. An approved Calibration Kit is also available. We can help define your unique turboprop engine test needs.

Reliable & Accurate

  • State-of-the-art Control Cab options and sizes
  • Optional ENDAS II or ADAQ™ controls, throttle & software
  • Only stand offering renowned Syncrophaser, HS EPCS, Prop Feather Controller & Vibe Monitor
  • ADAQ™, throttles and FADEC controls
  • Modern power/source distribution
  • Enhanced noise & climate control (A/C-Heater)
  • Run-up trailer with non-skid deck, non-halon fire suppression, larger hoist, double pane windows, boom and hoist control, common tie downs, updated electrical and other upgrades
  • Fuel module tank meets military requirements
  • Pump and valves controlled via control cab
  • Flexible cabling to engine, adaptable to different engines and test stand architectures
  • Run-up trailer, fuel trailer, and control cab are designed for easy transport and set up
  • CG is marked with tie downs matched to C130, C17, C5, & military air ride tractor trailers
  • Structural upgrades for T56 A425 & A427 with HS 54H60 (4 blade), Series 3.5 upgrade, HS NP2000 (8 blade) and J models/AE2100 with Dowty R391 (6 blade) or other props
  • T-56, T38, 501D and AE2100 used on: C-130/C-130J Hercules, LM-100, P-3 Orion, EP-3 Aries, E-2 Hawkeye, C-2 Greyhound, C-27J Spartan, Electra L-188, Convair CV 240, 580, 5800, Aurora CP-140, ShinMaywa US-2, AS Super Guppy, IA/IPTN N-250, Saab 2000


Advantages of Prop-On Testing/T21

  1. T21 Prop-on testing delivers full Propeller and Engine testing under optimal operating conditions, yielding more accurate, all-parameter results.
  2. T21 can be configured to Prop-on test all T56, T38, 501D and AE2100 engines.
  3. Post testing transition, turnaround and transport of engines to on-aircraft installation is minimized. Engines are ready with propeller and all types of testing complete.
  4. A majority of failure modes involve the propeller, and T21 Prop-on testing appropriately addresses these important maintenance requirements.
  5. Propellers and propeller control systems testing functions are seamlessly accomplished during engine run testing.
  6. T21 Prop-on testing uniquely facilitates integral checking of the Prop Feather Controller, Vibe Monitor, Synchrophaser, new HS Electronic Pitch Control System, and other control subsystems.
  7. Engine and Propeller installation, removal and handling is accommodated by the integral hoist rather than requiring field cranes or forklifts. This generates: better safety, labor savings, and streamlined maintenance and handling processes.
  8. Prop-on testing is particularly attractive for the low MTBF of these engines and propeller systems. T21 Test Stand efficiency is repeatedly beneficial to the maintainer for required frequent adjustments.
  9. Dynamometer O&M costs and complications are eliminated. T21 Prop-on testing is environmentally green, with no cooling water to treat or dispose.
  10. T21 is portable. Should a need arise to test in another location, the system can be easily moved without leaving behind facilities, equipment or other assets.