What Pilots and Maintainers Say About CDB
Craig Ernst – Test Pilot
The Customized Dynamic Balancing (CDB) process was a demonstration, not a
test, which was conducted here at AATD on behalf of the Apache PM. The Apache PM
had a "witness" present to observe and report his findings to the PM.
The CDB is a system/process that was designed by a Company called Shake'd
Technologies and is marketed in the U.S. by Coker Logistics Solutions, Inc
(CLS). It was CLS who solicited the Apache PM to allow them to demonstrate this
system.
The concept of operation is simple. There are accelerometers temporarily placed
in designated locations along the drivetrain, along with sensors to measure
shaft RPM and vibration. The aircraft is then run on the ground and measurements
are taken. All the data is pumped into a computer with the specialized software
written by Shake'd technologies and a balancing solution is determined.
Depending on the aircraft vibration condition, the driveshafts are balanced by
indexing the driveshaft, adding weight tape to the inside of the driveshaft in
specific locations.
We did CDB on two of our Apaches, AH-64A 120 and AH-64D 006. I have flown both and
can tell you that it has made an obvious difference. Not only are the vibrations
way down, it seems that the noise in the cockpit is quieter. We are impressed
enough that we would like to arrange for these guys to return and do AH-64A 214
for us as it was not available during the demo.
CW4 George Wheeler – Test Pilot
First of all I want to say that the members of the CDB team have a very
thorough knowledge of the AH-64 aircraft. Their ability to reduce vibration
levels down so low and accurately has been able to increase the life of
components and therefore reduce overall cost. With the modification of their
equipment and the accuracy of their findings they have reduced the run times to
just one adjustment most of the time. Which help us because it frees the test
pilots to work on other issues.
I think this will be an excellent addition to the aircraft especially once it is
incorporated into the MSPU. With the addition of sensors in other critical
locations, it will further improve our ability to detect issues with the
aircraft before it escalates to the failure of a component and possible saving
lives and equipment. That in itself makes it worth having the program.
I hope that we continue to use this program and increase it's utilization to all
our aircraft.
CW2 Tyson Le Roy – Test Pilot
Customized Dynamic Balancing has been an important tool in managing
vibrations on the AH-64D. With the AVA, and with the much more accurate MSPU, we
have been able to identify components that are potential sources of damaging
vibration. At the unit level, the mission was to identify a faulty component and
replace it. CDB has taught us that it is possible to reduce vibrations in
individual components by managing the sum of vibrations on the system as a
whole. This has saved our unit money, man-hours, and most importantly failures
of the components. MSPU is an excellent tool in collecting data from the
airframe, and identifying components that are near or have exceeded their
thresholds. CDB provides a solution to the problem that MSPU identifies.
MSPU with the addition of CDB solution algorithms has been an effective system,
which has set our test aircraft apart from our baseline aircraft. In our test
aircraft, CDB has been effective in solving high frequency conditions
experienced by our aviators. They were able to identify both non-rotating and
rotating components that are not directly monitored. In one particular case, a
loose tail rotor pedal bell crank, in another it was a bad precooler fan. Both
are components that are not monitored, but have tell tale vibrations.
Beyond the ability to reduce vibration in the aircraft as a whole, CDB has had
an important impact on the safety of the aircraftʼs monitoring system. Through
the process of balancing the aircraft the team has identified eight faulty
accelerometers. The problem is that the accelerometers are only put through
resistance check, and are not checked for accuracy. So even if a component were
to fail, it may or may not be flagged. This is an important issue that CDB
solves in a creative way. Another problem with the system we have found is that
if certain wires in the system break, they will prevent the illumination of the
VIB GRBX caution message. Shaked has identified a number of broken wires. The
identification of faulty accelerometers and broken wires has made the test
aircraft a much safer airframe to our aviators.
Customized Dynamic Balancing is an important program in our unit. It has
increased the safety and reliability of our test aircraft. My sole frustration
is having access to this resource only for a few tail numbers. My goal is to see
the whole battalion balanced.
It is a very difficult thing to identify a problem on one aircraft, and have no
way to check the other airframes. The ability to troubleshoot rotating and
non-rotating components without simply replacing parts is an important
capability that should be released for use on the all twenty-four aircraft of
1-130th ARB.
CW3 John Piland – Test Pilot
My impression of CDB is great. I think this is great way to improve overall
vibration in the drivetrain and reduce component wear. I can feel the
difference; reduce in vertical IPS in the seat and inside the aircraft while
adjustments are being made on the ground after each engine run-up. Our biggest
vibration is coming from the rotor system. High time blades opposite from low
time blades. Multiple blade repairs on the blades make the blade fly lower and
you will run out of trim tab adjustment. Flying with weak trim tabs on the main
rotor blade cause them to wash out during higher speeds. One reason is because
of improper phasing and static balance of main rotor blades. The static balance
is out of limits coming from depot on the last 4 new blades we got. Improper
phasing comes from worn Main rotor dampeners there is no way to check for this
on MSPU accurately or from the IETM. The lack of time to sweeten the main rotor
versus get it with-in limits as per MSPU which is .30 IPS Max for the green.
I hope this system will be implemented into the MSPU software. I would like to
see some of the limits on the Tail rotor balance, 90 deg, and IGB gearbox
reduce. I understand why the Ah-64a the vib gearbox light came on more often
then the Ah-64d MSPU equip aircraft because the limits are set higher on the
Ah-64D. CDB found some Aircraft non-MSPU the vib gearbox light would not have
came on because of bad accerlometer or processor. An indication inside the crew
station that tells me which clutch primary or secondary is engaged. I would like
to see the CDB train the 15R10 level at the schoolhouse and at the units on the
importance of indexing the driveshaft's before you remove them. Teach the MTP
what flight profile to fly and take a measurement to determine if you have a bad
m/r dampener or not. How to check for loose APU mounts (we had three found prior
to gunnery). Thanks again for the support and lessons learned from your TEAM of
CDB personnel.