MIL-DTL-901E: High-Impact Shock Testing for Shipboard Rugged Computing Systems
Last reviewed: September 2026
MIL-DTL-901E is a U.S. Department of Defense detail specification that establishes high-impact shock testing requirements for machinery, equipment, systems and structures installed aboard U.S. Navy surface ships and submarines.
The purpose of MIL-DTL-901E testing is to verify that shipboard equipment can withstand severe shock loading associated with nuclear or conventional weapons effects, as well as certain environmental mechanical shocks encountered during operation.
For rugged computing systems used aboard naval platforms, MIL-DTL-901E testing can help demonstrate that mission-critical servers, storage systems, networking equipment and other electronics can survive extreme mechanical shock without creating a safety hazard or losing required functionality.
The current specification is MIL-DTL-901E, dated June 20, 2017. It superseded MIL-S-901D, which had been in effect since 1989.
What is MIL-DTL-901E?
MIL-DTL-901E is formally titled:
Shock Tests, H.I. (High-Impact) Shipboard Machinery, Equipment, and Systems, Requirements For
The specification applies to equipment installed aboard:
- Surface ships
- Aircraft carriers
- Submarines
- Other applicable naval shipboard environments
Unlike general-purpose environmental shock testing, MIL-DTL-901E is specifically concerned with the ability of shipboard installations to survive severe high-impact shock events.
The specification defines requirements for:
- Shock test categories
- Equipment grades
- Equipment classes
- Equipment types
- Mounting configurations
- Test fixtures
- Operating conditions
- Acceptance criteria
- Test reporting
- Shock qualification
- Extensions of previously approved shock tests
The appropriate test configuration depends on the equipment being evaluated, how and where it will be mounted aboard the ship, whether shock isolation is used and the requirements established by the applicable Navy Technical Authority or contracting activity.
What is the current version of MIL-DTL-901?
The current specification is:
MIL-DTL-901E
Date: June 20, 2017
Status: Active
Supersedes: MIL-S-901D, dated March 17, 1989
MIL-DTL-901E changed the designation from a military specification (MIL-S) to a detail specification (MIL-DTL) and significantly expanded the requirements and guidance associated with shipboard shock qualification.
Programs developed under older contracts may still contain references to MIL-S-901D. The applicable revision should always be confirmed against the program’s contractual and technical requirements.
What does MIL-DTL-901E test?
MIL-DTL-901E evaluates whether shipboard equipment and installations can withstand the mechanical shock produced by severe events without experiencing unacceptable structural or functional failures.
For electronic equipment, shock exposure may cause:
- Circuit boards to flex or crack
- Solder joints to fail
- Connectors to separate
- Storage devices to become damaged
- Components to break loose
- Chassis structures to deform
- Fasteners to loosen
- Cables to disconnect
- Cooling components to shift or fail
- Power interruptions
- Intermittent electrical faults
- Complete loss of system operation
MIL-DTL-901E testing is intended to identify vulnerabilities before equipment is deployed aboard a naval platform.
For mission-critical computing systems, surviving the mechanical event alone may not be sufficient. Depending on the equipment’s Grade and program requirements, the system may also be required to maintain or resume its required function.
Why MIL-DTL-901E matters for naval computing
Modern naval vessels depend on increasingly sophisticated electronic systems for:
- Command and control
- Intelligence
- Surveillance
- Reconnaissance
- Radar
- Electronic warfare
- Communications
- Navigation
- Cybersecurity
- Sensor processing
- Data storage
- Artificial intelligence
- Autonomous systems
- Weapons support
- Machinery control
High-performance processors, GPUs, storage devices and network components can provide enormous computational capability, but commercial electronics are not necessarily engineered to withstand the shock environment of a naval combat platform.
Rugged computing systems therefore require careful mechanical design, component stabilization, mounting and qualification to maintain system availability during demanding operating conditions.
MIL-DTL-901E test categories
MIL-DTL-901E defines several categories of high-impact shock testing.
The appropriate method depends on the size, weight, mounting arrangement and application of the equipment being qualified.
Lightweight shock testing
Lightweight shock tests are performed using a Lightweight Shock Machine (LWSM).
The test item is attached to a fixture on an anvil plate. Mechanical impacts are delivered to the test installation to subject the equipment to high-impact shock.
Lightweight testing is commonly appropriate for smaller components, subassemblies and equipment within the limits defined by the specification.
The test configuration, orientation, fixture and operating conditions must represent the qualification requirements established for the equipment.
Medium weight shock testing
Medium weight tests are performed using a Medium Weight Shock Machine (MWSM).
The equipment is mounted to an approved fixture and subjected to a defined series of hammer blows designed to simulate the high-impact shock environment encountered aboard a naval vessel.
MIL-DTL-901E specifies mounting orientations, operating conditions and test schedules based on the equipment classification and shipboard installation.
Heavyweight shock testing
Heavyweight shock testing is performed using an approved Floating Shock Platform (FSP) or related floating test platform.
This type of testing is commonly referred to as:
Barge testing or barge shock testing.
During a heavyweight shock test, the equipment is installed on a floating platform in a configuration representative of its shipboard installation.
Explosive charges are detonated underwater at prescribed positions relative to the platform. The resulting underwater shock wave transfers severe mechanical energy into the platform and the equipment being tested.
Multiple shots may be performed using different charge locations or geometries.
The equipment is monitored and evaluated to determine whether it satisfies the applicable acceptance criteria.
Heavyweight shock testing is one of the most demanding qualification processes for naval electronic equipment.
Medium weight deck-simulating shock testing
MIL-DTL-901E also provides for testing certain deck-mounted equipment on a Deck Simulating Shock Machine (DSSM).
The DSSM is designed to reproduce important dynamic characteristics associated with shipboard deck response while allowing applicable equipment to be tested at a land-based facility.
Under defined conditions and with approval from the appropriate Technical Authority, this approach can provide an alternative to certain floating-platform tests.
The applicability of DSSM testing depends on factors including equipment classification, installation and shock-response characteristics.
What are Grade A and Grade B under MIL-DTL-901E?
MIL-DTL-901E defines two shock grades based primarily on the importance of the equipment to ship safety and combat capability.
Grade A equipment
Grade A equipment is essential to the safety and continued combat capability of the ship.
Grade A equipment is therefore expected to satisfy functional requirements associated with its mission following the required shock exposure.
For rugged computing equipment, Grade A may be relevant when the computer supports mission- or safety-critical capabilities that must remain available during or following a shock event.
Examples could include computing equipment supporting:
- Combat systems
- Command and control
- Communications
- Navigation
- Machinery control
- Mission processing
- Sensor systems
The actual Grade designation is determined by the applicable program or Technical Authority rather than by the equipment manufacturer alone.
Grade B equipment
Grade B equipment is not essential to the safety or continued combat capability of the ship, but its failure following shock cannot create an unacceptable hazard.
For example, components or portions of the equipment should not break free during shock in a manner that could injure personnel, damage Grade A equipment or threaten the ship.
Grade A and Grade B therefore represent fundamentally different qualification objectives.
They should not be interpreted simply as different levels of “ruggedness.”
What do MIL-DTL-901E Classes I, II and III mean?
MIL-DTL-901E also classifies equipment according to the relationship between the equipment and shock-isolation devices used in the shipboard installation.
Class I
Class I equipment is required to meet applicable shock requirements without isolation devices installed between the equipment and the ship structure or foundation.
In practical terms, the equipment is generally evaluated in a hard-mounted configuration representative of its installation.
Class II
Class II equipment uses isolation devices between the equipment and the ship structure or foundation.
These isolation systems may include shock or vibration mounts designed to control the mechanical energy transferred to the equipment.
The isolation system becomes part of the qualified installation and must therefore be considered during testing.
Class I/II
MIL-DTL-901E also recognizes Class I/II equipment.
This designation applies when portions of an installation are required to meet shock requirements without isolation devices while other portions use isolation.
Class III
Class III equipment has shipboard applications both with and without isolation devices.
Because the system may be installed in either configuration, it may need to satisfy requirements representing both isolated and non-isolated installations.
This distinction is particularly important when evaluating rugged computer systems because adding shock isolators does not automatically make a product compliant with MIL-DTL-901E.
The complete installation—including the computer, mounting hardware, shock isolators and supporting structure—must be considered as part of the qualification strategy.
MIL-DTL-901E equipment types and Type A, B and C testing
MIL-DTL-901E distinguishes among three equipment types:
Principal unit
A principal unit is an item that directly performs a major shipboard function.
A shock test of a principal unit is designated a:
Type A test
Subsidiary component
A subsidiary component is an item that forms part of a principal unit and may require separate qualification under defined circumstances.
A test of a subsidiary component is designated a:
Type B test
Subassembly
A subassembly is a portion of a principal unit or subsidiary component.
A test of a subassembly is designated a:
Type C test
These Type A, B and C designations should not be confused with Grade A and Grade B.
Grade identifies the item’s importance to ship safety and combat capability.
Type identifies what level of equipment is being tested.
That distinction is important when interpreting MIL-DTL-901E qualification claims.
How is MIL-DTL-901E qualification determined?
MIL-DTL-901E qualification is more specific than simply saying a product “passed a shock test.”
Qualification can depend on variables including:
- Test category
- Shock Grade
- Equipment Type
- Equipment Class
- Shipboard mounting location
- Mounting plane
- Mounting orientation
- Equipment configuration
- Shock isolation system
- Supporting fixture
- Operating condition during testing
- Acceptance criteria
- Technical Authority approval
Changing any of these characteristics can potentially affect whether previous shock qualification remains applicable.
This is why buyers should evaluate the exact qualification associated with a product rather than relying only on a general “MIL-DTL-901E compliant” statement.
Does MIL-DTL-901E provide a certification?
MIL-DTL-901E is not a consumer-style certification in which the Department of Defense simply awards a universal MIL-DTL-901E badge to a product.
Instead, equipment is qualified against specific requirements and configurations through the required testing and approval process.
MIL-DTL-901E includes provisions for documenting shock-test results and Technical Authority approval.
A meaningful qualification should therefore identify information such as:
- MIL-DTL-901E revision
- Shock Grade
- Equipment Class
- Equipment Type
- Test category
- Mounting arrangement
- Product configuration
- Applicable restrictions or limitations
- Test report or qualification reference
When evaluating equipment, buyers should request documentation appropriate to the program’s requirements.
What does “MIL-DTL-901E tested” mean?
A claim that equipment is tested to MIL-DTL-901E should indicate that a defined configuration underwent an applicable shock test conducted according to requirements from the specification.
However, the phrase alone does not tell a system integrator everything needed to determine whether the product is appropriate for a specific installation.
Important questions include:
- Was it a lightweight, medium weight, heavyweight or deck-simulating test?
- Was the system Grade A or Grade B?
- What equipment Class applied?
- What Type of test was conducted?
- Was the system isolated or non-isolated?
- What mounting configuration was tested?
- Was the equipment operating?
- What configuration was installed?
- What acceptance criteria applied?
- What qualification limitations were identified?
A useful MIL-DTL-901E claim should provide enough information to answer these questions or make supporting qualification documentation available.
MIL-DTL-901E vs. MIL-S-901D
MIL-DTL-901E superseded MIL-S-901D, which was issued March 17, 1989.
Although the fundamental purpose remains high-impact shock qualification of shipboard machinery and equipment, MIL-DTL-901E provides substantially more detailed requirements and guidance.
The newer specification includes expanded information concerning areas such as:
- Equipment classification
- Test selection
- Test fixtures
- Installation
- Mounting
- Shock response
- Test procedures
- Approval requirements
- Qualification documentation
- Extensions of previous shock-test approvals
- Deck-simulating shock testing
The change from MIL-S to MIL-DTL reflects the document’s designation as a detail specification.
Older products and programs may still reference MIL-S-901D because qualification was originally performed under that specification.
Whether additional qualification to MIL-DTL-901E is required depends on the contract, configuration, application and Technical Authority requirements.
MIL-DTL-901E vs. MIL-STD-810 shock testing
MIL-DTL-901E and MIL-STD-810 both address shock, but they serve different purposes.
MIL-DTL-901E
MIL-DTL-901E focuses specifically on high-impact shock affecting shipboard equipment and installations.
It is closely associated with naval survivability and shock loading resulting from weapons effects.
MIL-STD-810
MIL-STD-810 is a broader environmental engineering and laboratory-testing standard.
Method 516 addresses mechanical shock associated with conditions such as:
- Transportation
- Handling
- Functional shock
- Equipment drops
- Crash hazards
- Other lifecycle environments
A rugged computer that satisfies MIL-STD-810 shock requirements should not automatically be assumed to satisfy MIL-DTL-901E.
Naval programs may require qualification to both standards because they evaluate different environmental conditions and failure mechanisms.
MIL-DTL-901E vs. MIL-STD-167
MIL-DTL-901E and MIL-STD-167 are also complementary standards.
MIL-DTL-901E addresses high-impact shock.
MIL-STD-167 addresses shipboard vibration.
Shipboard electronics may experience continual vibration from engines, propulsion equipment, machinery and the vessel’s operating environment throughout their service life.
MIL-DTL-901E instead evaluates the much more severe transient loading associated with shock events.
Rugged naval computing equipment may therefore need to satisfy both vibration and shock requirements.
How rugged computers are engineered for shipboard shock
High-impact shock survivability must be considered throughout the mechanical and electrical design of a computing system.
Important engineering considerations can include:
Chassis construction
The chassis must maintain structural integrity while transferring shock loads without allowing excessive deformation around critical components.
Crystal Group rugged computer systems use rugged chassis construction designed for demanding military environments.
Component stabilization
Processors, GPUs, memory, storage devices, power supplies and expansion cards can experience significant mechanical loading during shock.
Component retention and stabilization help prevent movement, connector separation and structural damage.
Circuit board support
Printed circuit boards can flex during shock events.
Mechanical reinforcement, mounting-point design and component placement can help reduce board deflection and loads on solder joints.
Storage-device protection
Storage devices and their connectors must remain secure during high-impact loading.
Solid-state storage can eliminate some mechanical vulnerabilities associated with rotating media, although the complete mounting and electrical configuration still requires appropriate ruggedization.
Power supply retention
Power supplies represent significant mass within many rack-mount computers.
Their mechanical attachment and electrical connections must withstand high acceleration loads without becoming loose or disconnected.
Expansion-card retention
GPU cards and other PCIe expansion devices can be large and heavy.
Commercial card-retention methods may be inadequate for severe shock environments, making additional structural support and stabilization necessary.
Cooling-system design
Fans, heatsinks and other thermal components must remain securely attached during shock.
Thermal and shock engineering must therefore be considered together rather than as separate design problems.
Shock isolation
Where permitted by the installation and equipment Class, shock isolation may be used to reduce the mechanical input transferred from the ship structure to the equipment.
Isolation-system selection requires careful engineering because mount stiffness, displacement capability, equipment mass and dynamic response all affect shock performance.
Why configuration control matters after shock qualification
Qualification generally applies to a defined equipment configuration.
Changes that appear relatively minor can affect shock performance.
Examples include:
- Different processors
- Larger GPUs
- Different power supplies
- New storage devices
- Additional PCIe cards
- Different internal brackets
- Changes in chassis construction
- Different connectors
- Changes to mounting hardware
- Different shock isolators
- Changes in system weight
- Changes in center of gravity
For long-lifecycle naval programs, configuration management is therefore an important part of maintaining qualification.
MIL-DTL-901E includes provisions addressing extensions of previously approved shock tests, but extensions are subject to the requirements of the specification and applicable Technical Authority approval.
Crystal Group’s experience with MIL-DTL-901E shipboard shock
Crystal Group designs and manufactures rugged computing systems for demanding naval and maritime environments where shock survivability can be critical to mission performance.
Crystal Group engineering capabilities include ruggedization techniques intended to protect systems from severe mechanical shock and vibration, including:
- Rugged aluminum chassis construction
- Structural reinforcement
- Component stabilization
- Expansion-card retention
- Rugged storage integration
- Shock-isolation solutions
- Thermal management
- Configuration management
- Custom mechanical design
- Qualification-test support
Crystal Group has also participated directly in MIL-DTL-901E heavyweight shock testing.
During testing of Crystal Group’s RS1.533S18G Rugged Server, the system was installed on a floating shock platform and subjected to four underwater explosive shots. Crystal Group reported that the server successfully operated through the test series and passed the barge shock test.
That experience provides Crystal Group engineers with first-hand knowledge of the demands placed on high-performance computing hardware during naval high-impact shock qualification.
Customers should verify the current qualification status, test configuration, Grade, Class and applicable documentation for the specific Crystal Group product being considered.
MIL-DTL-901E rugged computing applications
Shock-qualified rugged computing can support naval applications including:
- Combat systems
- Command, control, communications, computers and intelligence (C4I)
- Radar and sensor processing
- Electronic warfare
- Mission computing
- Network infrastructure
- Data recording
- Data storage
- Artificial intelligence and machine learning
- Cybersecurity
- Autonomous and unmanned systems
- Machinery-control applications
Crystal Group offers rugged computing solutions that can be configured for surface-ship and submarine applications, including:
- Rugged servers
- Rugged storage systems
- Rugged network switches
- Rugged embedded computers
- GPU computing systems
- Rugged displays
- Custom integrated computing solutions
Explore Crystal Group rugged computing products
Explore maritime computing solutions
Learn about Crystal Group testing standards
Questions to ask when selecting MIL-DTL-901E computing hardware
Before selecting a rugged computer for a MIL-DTL-901E program, consider asking:
- Is the specific configuration qualified to MIL-DTL-901E?
- Which revision of the specification was used?
- Is the qualification Grade A or Grade B?
- What equipment Class applies?
- Was a Type A, Type B or Type C test performed?
- Which shock-test category was used?
- Was the equipment qualified using a shock-isolated or hard-mounted installation?
- What shipboard mounting configuration does the qualification represent?
- Was the computer operating during testing?
- Which processor, GPU, storage and expansion-card configuration was tested?
- Have hardware components changed since the qualification test?
- Is the current configuration covered by an approved qualification extension?
- Is a shock-test report or qualification record available?
- Are there limitations associated with the qualification?
- Can the manufacturer support program-specific testing or qualification?
These questions can help determine whether a product’s existing qualification actually applies to the planned shipboard installation.
Frequently asked questions about MIL-DTL-901E
What is MIL-DTL-901E?
MIL-DTL-901E is a U.S. Department of Defense detail specification establishing high-impact shock testing requirements for machinery, equipment, systems and structures installed aboard surface ships and submarines.
What is the current version of MIL-DTL-901?
The current specification is MIL-DTL-901E, dated June 20, 2017. It superseded MIL-S-901D.
What does the “E” in MIL-DTL-901E mean?
“E” identifies the revision of the specification. MIL-DTL-901E superseded the previous MIL-S-901D specification.
Is MIL-S-901E the same as MIL-DTL-901E?
MIL-DTL-901E is the correct designation for the current specification. The predecessor was MIL-S-901D. The terminology “MIL-S-901E” is sometimes used informally or incorrectly, but the official current designation is MIL-DTL-901E.
What is MIL-DTL-901E barge testing?
Barge testing is a common term for MIL-DTL-901E heavyweight shock testing conducted using an approved floating shock platform. Underwater explosive charges produce shock loading that is transferred through the floating platform to the installed test equipment.
Does MIL-DTL-901E require explosives?
Heavyweight floating-platform testing uses underwater explosive charges. Lightweight and medium weight testing, however, use mechanical shock machines rather than underwater explosives. MIL-DTL-901E also includes provisions for other approved test approaches.
What is Grade A MIL-DTL-901E equipment?
Grade A equipment is equipment essential to the safety and continued combat capability of the ship.
What is Grade B MIL-DTL-901E equipment?
Grade B equipment is not essential to the ship’s safety or continued combat capability, but its response to shock must not create an unacceptable hazard to personnel, Grade A equipment or the ship.
What is the difference between Class I and Class II?
Class I equipment is required to meet applicable shock requirements without isolation devices between the equipment and ship structure or foundation. Class II equipment uses isolation devices as part of the qualified installation.
What is Class III MIL-DTL-901E equipment?
Class III equipment has applications both with and without shock-isolation devices and therefore may need to meet requirements representing both configurations.
What do Type A, Type B and Type C mean?
Type A refers to testing a principal unit, Type B refers to testing a subsidiary component and Type C refers to testing a subassembly.
Is MIL-DTL-901E the same as MIL-STD-810?
No. MIL-DTL-901E specifically addresses high-impact shock of shipboard equipment. MIL-STD-810 is a broader environmental engineering and laboratory-testing standard covering shock as well as temperature, vibration, humidity, altitude, sand, dust and other environmental conditions.
Is MIL-DTL-901E the same as MIL-STD-167?
No. MIL-DTL-901E addresses high-impact shock, while MIL-STD-167 addresses vibration of shipboard equipment. Naval systems may be required to satisfy both.
Does passing MIL-STD-810 shock testing mean a computer meets MIL-DTL-901E?
No. The standards use different test methods and address different environmental conditions. MIL-STD-810 shock qualification should not be considered a substitute for MIL-DTL-901E qualification when the latter is required.
Does a product have to be tested again if its hardware changes?
Not necessarily, but configuration changes must be evaluated to determine whether the existing shock qualification remains applicable. MIL-DTL-901E includes provisions for extending previously approved shock tests under specified conditions and with the required approval.
Engineer shipboard computing for shock survivability
Rugged computing intended for naval deployment must do more than deliver processing performance.
The system’s chassis, components, storage, power, cooling, mounting and shock-isolation strategy must work together to withstand the severe mechanical loading associated with shipboard operation and combat environments.
Crystal Group combines rugged mechanical engineering with high-performance commercial computing technology to develop shipboard computing solutions tailored to program, platform and qualification requirements.
Whether a program requires an existing shock-qualified product or a customized solution designed around specific MIL-DTL-901E requirements, involving rugged-computing engineers early can help reduce qualification risk, redesign and program delays.
Talk with a Crystal Group rugged computing specialist