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MIL-STD-810 Method 520 Temperature, Humidity, Vibration and Altitude Testing

MIL-STD-810 Method 520 evaluates equipment's ability to withstand and operate under combined environmental stresses of temperature, humidity, vibration, and altitude. For over 30 years Clark Testing has been providing Method 520 testing to assess the equipment's performance in challenging conditions under combined harsh environments during field operations.

This Method exposes equipment to simultaneous controlled levels of temperature, humidity, vibration, and altitude to evaluate the effects of combined environmental conditions on components and materials. The affected material includes airborne electronic and electro-mechanical materials that can affect the safety and overall performance during ground and light operations.

The intent of Method 520 is to apply ideal combinations of stress to the material to determine performance and capabilities. All of the conditions such as altitude, vibration, and absolute humidity testing can be combined to increase the operational stresses and expose potential equipment failures when compared to the effects of individual environments.

After examining equipment validation requirement documents, Clark’s test engineering team will determine where the functions of temperature, humidity, vibration, and altitude are applied in the lifecycle of the material in the field of operation. We will conduct the engineering analysis and coordinate a test plan to perform the appropriate environmental stresses associated with the individual test methods thereby encompassing the complete test application.


The typical result of extreme temperature, humidity, vibration, and altitude can combine synergistically to produce the following failures:

  • Shattering of glass vials and optical material
  • Binding or loosening of moving parts
  • Separation of constituents
  • Performance decline in electronic components due to parameter shifts
  • Electronic optical (fogging) or mechanical failures due to rapid water or frost formation
  • Cracking of solid pellets or grains in explosives
  • Differential contraction or expansion of dissimilar materials
  • Leakage of sealed compartments
  • Failure due to inadequate heat dissipation

Method 520 includes three temperature, humidity, vibration, and altitude test procedures. When selecting a military standard test procedure, the anticipated life cycle of the product must be used as a general guide to conditioning and choosing the correct procedures. The choice of test procedures is determined by the developmental phase of the equipment.

In general, the test purpose will drive the selection of the test procedure. The choice of test procedure is predicated by the in-service condition of the equipment including temperature, humidity, vibration and altitude environments, and the test purpose.

Procedure I - Engineering Development is applied to find defects in a new design while it is still in the development stage. This procedure is

accelerated and failure-oriented, such that it is more likely to uncover design defects compared to using a more

benign procedure.

Procedure II - Flight or Operation Support, is performed in preparation for, during, and after flight or operational testing. Its purpose is to use

laboratory testing in lieu of flight testing to more quickly evaluate environmental problems discovered in flight


Procedure III - Qualification testing is intended to demonstrate compliance with contract requirements. Often, qualification testing is an accelerated test that emphasizes the most significant environmental stress conditions.

The Clark’s test engineering team will help determine test levels and test cycle formulation to select the method and relevant procedures based on the test item's requirements documents and the tailoring process by identifying appropriate parameter levels, special test conditions and techniques for these procedures. The selection of test levels will be based on the requirements documents and the Life Cycle Environmental Profile (LCEP), and information provided with this procedure.

Email the Clark Dynamic Test laboratory for additional information on how we can help the you navigate the Equipment Qualification (EQ) process to validate or certify you equipment or components in accordance with MIL-STD-810G Method 520

Test Set Up

In house custom design and fabrication capabilities (machining and welding) to ensure test fixtures accurately simulation environmental conditions.  FEA capabilities to support fixture design along with welding, fabrication & machining services.  Multiple vibration adapter plates and prefabricated test fixtures help to streamline the testing process.

Instrumentation capabilities including accelerometers and strain gages with multi-channel control and data acquisition equipment ensuring accurate test data is being recorded.  All instrumentation and equipment is provided with measurement uncertainty and compliant   with Clark’s ISO 17025-2017 Quality Program.

Lab technicians and engineers record daily test activities to register all activities, events, and responses during the test.  The daily test logs along with test data, pictures and test procedures are included in comprehensive test report that is the industry standard.

 We work closely with you to validate engineering, ensure quality, analyze test spectrums, and execute accurate testing programs for successful qualification and marketing of your product.

We work closely with you to validate engineering, ensure quality, analyze products and qualify equipment while supporting the time constraints and product cycles that are vital to your success.

Paul Heffernan, CEO of Clark Testing