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Latest News in Testing, Inspection and Certification

NTS News Center - Latest News in Testing, Inspection and Certification

How will MIL-DTL-901E affect your shock qualification?

Photo: Navy.com

For the past 30 years, MIL-S-901D has defined requirements for shock qualification of items installed on U.S. Navy Combatants. For the duration of this period, there have been rumors of a new and improved specification revision. That time has finally come.

MIL-DTL-901E, revision to MIL-S-901D of 1989 has been approved and released as of 20 June 2017. The new “detail specification” or DTL per DOD 4120.24M is an evolutionary document that includes changes from MIL-S-901D, Interim Change #2, the 2012 DSCR-2 initiative clarification letters and cost reduction strategies, and the Total Ownership Cost (TOC) reduction provided by the Deck Simulating Shock Machine (DSSM).

For most Navy shipboard shock practitioners, the most impactful change to the document is the addition of the Medium Weight Deck Simulating Shock Test.  This test is primarily performed on Class II, deck mounted equipment and utilizes the DSSM. The DSSM is typically used in lieu of performing a heavyweight shock test series.

The DSSM shock test machine at NTS Rustburg

In the early 2000s, we recognized that the current model for shock qualification of a vast majority of the proliferating Class II, Deck Mounted, COTS equipment was not sustainable from a costs and schedule perspective.

So, in collaboration with HII-NNS partners, NTS led the pioneering development of a more cost and schedule effective land-based approach to meet this new challenge. These efforts culminated in the fabrication of the DSSM Generation I machine that has been in use at NTS Rustburg, VA since 2004.

The success of the Generation I DSSM led to the development of a scaled-up Generation II machine that is specified in MIL-DTL-901E. All of the certification testing that was necessary prior to inclusion in the new MIL-DTL was conducted at NTS. We have been routinely conducting shock qualification testing on the DSSM as an Alternate Shock Test Vehicle since 2015.

The DSSM development is yet another example of NTS’ focus on customer driven innovation. If you have questions concerning the new MIL-DTL-901E detail specification and how it may affect your program or have a need for Medium Weight Deck Simulating Shock Tests contact our experts today!

Extreme Cold Testing

Thermal Shock Chamber

Thermal Shock Chamber at NTS Tempe, AZ

Environmental testing has been a major component of NTS services since our founding in 1961. Military and commercial standards such as MIL-STD-810 and RTCA/DO-160 include sections for thermal shock, icing, freezing rain, and hail impact.

Thermal shock testing  lies at the most severe end of the spectrum of temperature tests performed by NTS. Thermal shock refers to a very high rate of temperature change and is generally conducted on aircraft components, military hardware and electronics designed to withstand harsh environments.

Because almost all products are subject to shipping, this test may be appropriate for any part that will have to withstand an abrupt temperature change in a short period of time, such as a transition from environmentally controlled storage to the varying environments encountered during transport.

Air-to-air thermal shock testing is the most common test performed at our laboratories. It is conducted by moving the test article from one extreme temperature to another on a mechanical conveyor or elevator, depending upon the orientation of the chambers. Fully enclosed thermal shock test chambers keep the equipment stationary while the chamber temperature cycles.

For very large items that cannot be moved by an in-chamber elevator, NTS can provide fixtures and the right setup to meet applicable test specification requirements while assuring the safety of the test item. In one such case, NTS engineers in Boxborough, MA were faced with the challenge of performing icing testing a on a tall telescoping antenna while it was under operation. A custom 23’ x 7’ 7” chamber with temperature controls was built to accommodate this extreme test.

Other examples of specialty thermal shock testing include a liquid-to-liquid system in which a basket is utilized to mechanically transfer a test article from one vat to another for a higher transfer rate of greater thermal energy. NTS also performs cryogenic testing for launch vehicles, satellites, and related hardware. Two large capacity LN2 pits are available for testing that requires either simple atmospheric or highly pressurized sub-freezing temperature shock.

Give us a call today at 800-649-5289 to discuss your extreme environmental testing!

Movers and Shakers at NTS Fullerton

_WI06432There are some good vibrations going on at NTS Fullerton. After months of construction and streamlining our Dynamics Department is operating in a state-of-the-art facility. The newly constructed building incorporates a 16 ton crane and efficient open floor space. This floor space allows for customizable dual-shaker setup for the testing of over sized items. Using C220 shakers and the 16 ton high powered crane the dual-shaker setup can put out a combined 70,000 force pounds.

Staged on a versatile platform with a 500,000lb reaction mass the Dynamics Department houses nine Electrodynamic Shakers including two MB C220, four UD T1000, one UD T4000 and one UD T2000 with test capability ranges up to 32,000 lbF, 3,000 Hz and displacement ability between 1” to 3”. There are also three hydraulic shakers including a TEAM Hydraulic shaker capable of 12,000 lbF and up to 500 Hz and two Windmilling Hydraulic Shakers capable of 3,000 lbF and up to 50 Hz. We also feature a multitude of Drop Shock towers ranging from 8 feet to 40 feet high.

Of course, none of this would be of any value without the right support equipment. NTS Fullerton has invested in various vibration and shock controllers to support a wide range of test situations. With Spectral Dynamics Jaguar controllers and Spectral Dynamics 255X controllers the Dynamics Department has the ability to support anywhere from a 4 channel up to a 64 channel reading.

NTS Fullerton prides itself on being able to execute testing and engineering programs with focus and excellence. Being willing to customize solutions to support your unique product design is key to achieving that goal. NTS Fullerton maintains a SEA compliant in-house machine shop, design engineers and partners with industry leading precision machining companies to ensure that each program is complete from planning to execution to reporting.

For more information on NTS Fullerton’s complete capabilities review our brochure or for a firsthand look contact us to schedule an onsite tour of the facility at (714) 879-6110 or heather.bennett@nts.com