by Senior Airman Charles Rivezzo
60th Air Mobility Wing Public Affairs
10/9/2015 - TRAVIS AIR FORCE BASE, Calif. -- Officials
from Lockheed Martin and Travis Air Force Base successfully recorded
in-flight noise and vibration data onboard a C-5M Super Galaxy Sept. 24,
ensuring that the recently upgraded airframe was still compliant with
the National Aeronautics and Space Administration requirements.
According to Brian Austin, a Lockheed Martin representative assigned to
the 60th Maintenance Group, the objective of the test was to collect
interior noise and vibration data to verify that the C-5M Space Cargo
Modified (SCM) cargo compartment still met the vibroacoustic
requirements set forth by NASA.
In order to record the data, engineers strategically placed 12
microphones, five single axis accelerometers and four triaxle
accelerometers throughout the aircraft's specially modified cargo
Austin added that while the data gathering facet of this test has been
deemed a success, the data is currently being analyzed to verify the
One of only two C-5Cs - an aircraft specially modified to carry
satellites and other large cargo - the aircraft recently returned here
after being retrofitted with General Electric CF6-80C2 engines and
modernized as part of the C-5M Reliability Enhancement and Re-Engining
Because the new engines provide the C-5 with 22 percent greater takeoff
thrust - potentially altering the vibrations generated within the cargo
compartment - Air Force Space Command raised concerns that the aircraft
be reevaluated to verify the aircraft sill met NASA requirements.
NASA is currently one of the C-5C's largest customers and has utilized
it to carry satellites, components of the Space Station and the Hubble
Unlike traditional C-5s, the C-5M-SCM's aft troop compartment was
removed and special modifications were made to their rear loading doors,
creating a larger cargo area that can accommodate and transport the
Space Container Transportation System.
The need to record the vibratory environment of the cargo compartment
primarily stems from just how tight the SCTS canister is placed into the
airframe. On average, the clearance between the canister and the walls
and ceiling of the aircraft is approximately one inch, leaving little
wiggle room should the cargo shift within flight. On and off-loading
from the aircraft is an operation that can take hours to complete as the
canister is basically inched out of the cargo bay.
Currently, C-5M-SCM serial number 68-0213 is the only aircraft suitable
for SCTS transportation as 68-0216 recently departed to undergo the RERP
upgrade and is not slated to return until late 2017.