3U - HES-FBL - Front-to-Back loaded with 4 Heat Exchangers

Rugged SEALED COTS 3U ATR. Available in 3, 5, 7 & 9 slot versions, supporting up to 300 watts payload. Certified per MIL-461F & MIL-810G for immediate deployment.
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3U - HES-FBL - Front-to-Back loaded with 4 Heat Exchangers

Custom COTS - Customer configurable & loaded with options: Extended bottom & top covers, front panel connectors, logos & silk screening, etc.
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3U ATR HES-FBL Description

Sealed, 1" pitch, high performance dry-air 3U chassis incorporates four heat exchangers and air re-circulation fans inside. This conventional format chassis is ideal for applications where ambient air is laden with hostile or harmful contaminants.


Heat generated within the enclosure is conducted to the hollow sidewalls, top cover & rear panel heat exchanger where it is dissipated to the ambient environment by forced air rear fans or by vehicle platform air plenum. Internal air recirculation fans ensure constant airflow across modules.


The 3U HES-FBL chassis is available in 3, 5, 7 & 9 slot versions, supporting VPX & cPCI-S backplanes. A total PSU power of up to 575 watts may be installed. Custom modifications can be designed upon customer request.


Internal layout is divided into 4 independent metallic partitions. I/O section at the front, card-cage, PSU section & exhaust fans at the rear. This improves EMI/EMC performance & reduces PSU noise on system electronics.

Conventional "front-to-back" configuration allows for convenient appication upgrade and expansion, keeping the same PSU, Front Panel and Fan Packs across systems. The chassis card-cage is designed for wedgelock IEEE P1101.2 conduction-cooled card types.

3U HES-FBL Performance



Slots / Pitch:3 | 5 | 7 | 9   1"

Sealed (Dry Air):

≤ 300W

The 3U HES-FBL chassis is suitable for high wattage sealed applications that demand superior cooling capability and increased life-cycle scalability. This series of chassis provides the greatest expansion felxibility, system interoperability and lowest upgrade costs for advancing platforms.

HES-FBL - Chassis Payload Thermal Resistance (CPTR):
HES-FBL 3 Slot: 200W Payload Power (ΔT/W = 0.15°C).
HES-FBL 5 Slot: 250W Payload Power (ΔT/W = 0.12°C).
HES-FBL 7 Slot: 270W Payload Power (ΔT/W = 0.11°C)..
HES-FBL 9 Slot: 300W Payload Power (ΔT/W = 0.10°C)..

For reliable operation it is recommended the maximum Payload Power not be exceeded. Subject to operating conditions. All CM 3U ATR chassis are delivered tested, qualified and certified per Military Standards MIL-STD-461E & MIL-STD-810F.

3U Backplanes

CM 3U backplanes are low noise, full military VMEbus, VPX or cPCI-S compatible and provide fully standard bus slot & signal daisy-chain functionalities. Bus slots are tailored for 1 inch pitch standard & deliver full compatibility with 0.8 inch pitch 3U modules.

CM-ATR-3U/ - Backplanes

CM 3U enclosures incorporate a versatile universal ‘MCS’ slot mixed card-cage that accepts all off-the-shelf Conduction Cooled and Air Cooled 3U modules.

An alternative ‘CCS’ conduction cooled card-cage is available for conduction-cooled boards only, whereby improving thermal performance.

All 3U backplanes install specific TTL logic circuitry for driving up to 8 front panel user LED indicators.

All 3U backplanes integrate a Temperature Supervisory Unit (TSU) with panel LED (over/under temperature) that controls Power Supply & Fan operation. Remote optoisolated control switches for ‘Battle-short’ & chassis PSU ‘on/standby’ are fitted as standard.

CM-ATR-3U/ - Backplanes
  • VME64x backplanes. Conduction-cooled IEEE-1101.2 modules.
  • VPX backplanes conform to VITA 46 / 65 / 66 / 67 (≥10 GHz Gen 3).
  • Compact PCI Serial backplanes according to PICMG CPCI-S.0 R2.0 2015 / IEEE 1101 standards.

CM 3U military backplanes allow unlimited pin I/O wiring capability. Flexible top & bottom wiring integration is facilitated by a standard 25mm bottom cavity clearance.

Class 1 military power input connectors fitted on the backplane offer shock & vibration reliability interconnectivity between chassis internal modules & allows high DC current rates with low voltage drops and minimum contact heating.

CM-ATR-3U/ - Backplanes

3U backplanes are supplied with military conformal coating. Printed circuits boards are partially coated per MIL-I-4658C. This is carried out only in areas in which coating the product does not affect VPX, VME, cPCI or I/O connectors.

All 3U models integrate the same backplane electronics for easy switch-overs, retrofits or replacement parts.
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3U HES-FBL Power Supplies

3U HES-FBL chassis PSUs support a wide variety of AC/DC input voltages (MIL-STD-704 & MIL-STD-1275) and customer defined DC power output combinations up to 575 Watts. Available in 6 different versions (A-B-C-...) to suit the demand per DC Line of standard COTS open busses.


All PSU models are fitted with Power Fail Monitor, remote voltage sensing, output voltage trim-up, time-delayed protection fuses, rear fan fuse and DC/DC converter remote shutdown.

To comply with MIL-STD-461G, a high capacity integrated EMI/EMC input voltage filter is fitted as standard on all 3U models. All models integrate the same PSU and backplane electronics.

Single-phase AC PSUs are fitted with a VICOR military Filter and Autoranging Rectifier Module (FARM) to provided EMI filtering, autoranging line rectification and inrush current limiting to meet MIL-STD-461E category A1b specifications for Electromagnetic Compatibility.

3U HES-FBL Power Supply Unit

200VAC 3-Phase PSU versions additionally incorporate AC/DC rectifier stage prior to the VICOR FIAM front-end modules.

DC PSUs are equipped with a VICOR military Filter and Attenuator Module (FIAM). This front-end device is fitted prior to the DC/DC converters to provide EMI filtering, inrush current limiting and transient protection.

Front-end FIAM modules are protected against DC reverse polarity. An optional reverse polarity diode may be fitted in series with power connector input pin IN (+).

3U HES-FBL PSUs incorporate isolated DC/DC converters and oversized hold-up capacitors to ensure proper operation during short power line failures. Outputs are protected against short-circuit, thermal-shutdown etc. PSUs are custom made to match the enclosure mechanics.

3U HES-FBL Power Supply Unit

The PSU in HES-FBL models is attached to a heat exchanger panel that provides both conduction and convection cooling. Internal air recirculation dissipates heat generated by the PSU through its panel via thermal conduction to the chassis frame.

Forced air that is drawn through the heat exchangers, passing over the PSU panel external fins & exhausted, removing the majority of heat.

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3U ATR HES-FBL Features

3U HES-FBL Rear Fan Assembly
Rear Fan Options
3U HES-FBL chassis fits twin Rugged (-10°C to +70°C) exhaust fans as standard. Military PX2 fans are optional (-54°C to +125°C).
3U HES-FBL LED Indicators
LED Front Panel Indicators
Up to 8 front panel LED indicators for chassis monitoring; power on/off status, system board failure, input voltage, temp., etc.
3U HES-FBL Front Panel
Front Panel
Custom layout with client logo, connectors & silk-screening or a general purpose panel with MIL-C-38999 connectors is supplied.
3U HES-FBL Life-cycle Scalability
Product Flexibility
HES-FBL 3-5-7-9 slot chassis install the same Front Panel, PSU & Fan Pack, making system upgrades cost effective for application expansion.
3U HES-FBL Chassis Metalwork
Chassis Metalwork
Precision machined aeronautical aluminum with MIL-DTL-5541F chromate coating. All panels & joints incorporate EMI gaskets.
3U HES-FBL Mounting Tray
Mounting Tray
Low profile with quick release system offers easy insertion/removal capability, weight optimized with minimized dimensions.
EMI/EMC Filter
High capacity integrated EMI/EMC input voltage filter is fitted as standard on all 3U models to comply with MIL-STD-461F.
3U HES-FBL Internal Air Recirculation
Air Recirculation
All 3U chassis incorporate a low profile internal fan pack to recirculate air, improving card-cage, PSU & module heat dissipation.
3U HES-FBL Conventional Card-cage
Conventional Card-cage
A conventional Front-to-Back conduction-cooled card-cage where module wedge-locks meet cool sidewalls by the closest path.


  • Contaminant-free enclosure
  • Accepts Conduction-cooled 3U Modules only
  • Flexible Bottom I/O wiring
  • In-line EMI/EMC MIL-STD-461G Filter
  • Up to 300W* Total Payload Power (30ºC Delta-T)
  • 4 Integrated Heat Exchangers
  • Integrated Chassis Supervisory System (CSS)
  • 20°C less than conventional 3U ATRs
  • Dramatically increases payload MTBF by 4x*
  • Maintenance free operation
  • Front panel user indicators
  • Integrated Rear fan guards
  • Independent Fan & Power Supply input voltage
  • Stand alone low weight ATR
  • Internal card-cage airflow recirculation
  • Military Operating Temperature (-40°C | +85°C)
  • Customizable to specific requirements
  • Low Profile Mounting Tray with quick release
  • Manufactured with US MIL components
* Subject to operating conditions

3U ATR HES-FBL Specifications

WIDTH 134 mm 134 mm 134 mm 134 mm
HEIGHT 233 mm 233 mm 233 mm 233 mm
DEPTH 234 mm 285 mm 336 mm 387 mm
WEIGHT 5.0 Kg 5.8 Kg 6.6 Kg 7.5 Kg
CPTR COEFF ΔT/W = 0.15°C ΔT/W = 0.12°C ΔT/W = 0.11°C ΔT/W = 0.10°C
SLOTS 3 5 7 9
MAX PSU PWR 575 Watts (28 VDC 475 Watts)
PSU V-INPUT 28 VDC ±30%, 48 VDC ±30%, 72 VDC ±30%, 270 VDC ±30%, Autorange 90-132 VAC RMS & 180-264 VAC RMS 47-880 Hz, 3-Phase 200 VAC ±30% 47-880 Hz
STD BACKPLANE 3U (1" Pitch), VPX & cPCI-Serial R.2.0
BOARD FORMAT CCS: Conduction-cooled slots only ANSI-VITA 48.2 boards
INTERNAL FAN 1 x 13.5 CFM 2 x 13.5 CFM (27 CFM) 3 x 13.5 CFM (40 CFM) 4 x 13.5 CFM (54 CFM)
EXT. REAR FAN 2 Rugged or 2 Rotron PX2
STDF 120 CFM (Rugged)
F115-400 130 CFM (Rotron PX2)
F200-400 240 CFM (Rotron PX2)
FRONT PANEL AREA 96 mm x 140 mm
CM FRONT PANEL I/O 6 Power Pins (13 Amp) & 382 I/O Pins (5 Amp)
MTBF 25° GB 82,000 Hours, 65° AIC 27,000 Hours
OPERATING TEMP -40°C to +85°C Operating Temperature, -55°C to 100°C Storage Temperature


These highly optimized 3U chassis incorporate all proprietary technologies, features and well established mechanical & electrical solutions developed during the past 20 years.

FAC:Flow-through airflow open enclosure.

S:Standard sealed contaminant-free enclosure.

SEF-18HP:Sealed with Extended Fins + 18 Heat Pipes contaminant-free enclosure.

HES:Sealed contaminant-free enclosure fitted with 4 integrated heat exchangers as standard.

HES-FBL:Sealed, conventional front-to-back format contaminant-free enclosure fitted with 4 integrated heat exchangers as standard.

HES-FBL-HP:Sealed, conventional front-to-back format contaminant-free enclosure fitted with 4 integrated heat exchangers and heat pipes as standard.

3U ATR MIL Certificates

3U ATR Ordering Information

Generic Part Number:
CM-ATR-3U /CT /B /I /W /FP /TC /BC /CS /F /C
/CT Enclosure Cooling Technique
  • CM-ATR-3U/HES-FBL3: Sealed, 3 Slot with 4 Heat Exchangers.
  • CM-ATR-3U/HES-FBL5: Sealed, 5 Slot with 4 Heat Exchangers.
  • CM-ATR-3U/HES-FBL7: Sealed, 7 Slot with 4 Heat Exchangers.
  • CM-ATR-3U/HES-FBL9: Sealed, 9 Slot with 4 Heat Exchangers.
/B Backplane Type
  • VPX: VITA 46 Military 3U VPX Backplane (1" Pitch).
  • cPCI-S: Military Compact PCI Serial Backplane R2.0 (1" Pitch).
/I PSU Input Power Voltage
  • 28VDC: 28 VDC Input.
  • 48VDC: 48 VDC Input.
  • 72VDC: 72 VDC Input.
  • 270VDC: 270 VDC Input.
  • 90-264VAC: Autorange 90-264 VAC @ 47-880 Hz Input.
  • 200VAC-3Ph: 200 VAC 3 Phase @ 47-880 Hz Input.
/W Power Supply Unit
  • A-475W: 28 VDC* (+5 VDC @ 40A, +3.3 VDC @ 22A, ±12 VDC @ 8A).
  • A-575W: All PSUs* (+5 VDC @ 40A, +3.3 VDC @ 22A, ±12 VDC @ 12A).
  • B-450W: 28 VDC* (+5 VDC @ 20A, +3.3 VDC @ 45A, ±12 VDC @ 8A).
  • B-550W: All PSUs* (+5 VDC @ 20A, +3.3 VDC @ 45A, ±12 VDC @ 12A).
  • C-475W: 28 VDC* (+5 VDC @ 20A, +3.3 VDC @ 22A, +12 VDC @ 16A, -12 VDC @ 8A).
  • C-575W: All PSUs* (+5 VDC @20A, +3.3 VDC @22A, +12 VDC @21A, -12 VDC @12A).
All PSUs* = All PSUs except 28 VDC input
28 VDC* = 28 VDC input only

/FP Front Panel Layout
  • CMP: Standard CM front panel fitted with MIL-C-38999 connectors.
  • UDP: User defined front panel layout (requires customer drawing).
/TC Chassis Top Cover
  • STC: Standard Top Cover.
  • FTC: Finned Top Cover. Wiring clearance 13mm.
  • HTC: High-profile Top Cover. Wiring clearance 35mm.
  • HETC: Heat Exchanger Top Cover. No Wiring clearance (Fitted as standard).
/BC Chassis Bottom Cover
  • SBC: Standard Bottom Cover. Wiring clearance below backplane 24mm. (Fitted as standard)
  • HBC: High-profile Bottom Cover. Wiring clearance below backplane 49mm.
/CS Chassis Card-cage Slot
  • CCS: Conduction cooled Card-cage Slots (Conduction-cooled Boards Only).
/F Rear-mounted Fan Assembly
  • STDF: 2x 60 CFM DC Rugged Fans.
  • F115-400: 2x 65 CFM Rotron PX2 Military Fans fitted for 115 VAC @ 400Hz.
  • F200-400: 2x 120 CFM Rotron PX2 Military Fans fitted for 200 VAC 3-phase @ 400Hz.
/C Chassis Color
  • B: Black, G: Navy Grey, E: Army Dark Earth, W: White, R: Red, PT: Platinum, YW: Yellow, GN: Green, BLU: Dark Blue, CR: Chromate MIL-C-5541 or O: Other (user defined).
Part Number Example:
  • 5 slot, 3U Avionics Enclosure.
  • Sealed, conventional front-to-back ATR with 4 Heat Exchangers, top cover, sidewalls & rear panel.
  • 5 slot, 3U VPX backplane.
  • 115VAC @ 400 Hz input power supply.
  • C-575W Power Supply (+5VDC @ 20A, 3.3VDC @ 22A, +12VDC @ 21A, -12VDC @ 12A).
  • User defined front panel layout (requires customer drawing).
  • Heat Exchanger Top Cover. Wiring clearance 13mm.
  • Standard Bottom Cover. Wiring clearance below backplane 25mm.
  • Conduction Card-cage Slots (Conduction-cooled Boards Only).
  • 2x 60 CFM DC Rugged Fans.
  • Enclosure color is user defined.