IEC TR 62131-6:2017

IEC TR 62131-6 ®
Edition 1.0 2017-09
TECHNICAL
REPORT
colour
inside
Environmental conditions – Vibration and shock of electrotechnical equipment –
Part 6: Transportation by propeller aircraft
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IEC TR 62131-6 ®
Edition 1.0 2017-09
TECHNICAL
REPORT
colour
inside
Environmental conditions – Vibration and shock of electrotechnical equipment –

Part 6: Transportation by propeller aircraft

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 19.040 ISBN 978-2-8322-4828-7

– 2 – IEC TR 62131-6:2017 © IEC 2017
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Data source and quality . 8
4.1 Vibration survey of four different propeller driven aircraft . 8
4.2 Britten-Norman Islander aircraft flight measurements . 9
4.3 Lockheed C130 flight vibration measurements . 10
4.4 Lockheed C130 landing shock measurements . 12
4.5 Supplementary data . 12
5 Intra data source comparison . 14
5.1 General . 14
5.2 Vibration survey of four propeller driven aircraft . 14
5.3 Britten-Norman Islander aircraft flight measurements . 15
5.4 Lockheed C130 flight vibration measurements . 16
5.5 Lockheed C130 landing shock measurements . 16
6 Inter data source comparison . 16
7 Environmental description . 17
7.1 Physical sources producing mechanical vibrations . 17
7.2 Environmental characteristics and severities . 19
7.3 Derived test severities . 19
8 Comparison with IEC 60721 (all parts) . 20
9 Recommendations . 23
Bibliography . 59

Figure 1 – Instrumentation locations for Britten-Norman Islander aircraft [1] . 24
Figure 2 – Instrumentation locations for BAe Jetstream aircraft [1] . 24
Figure 3 – Instrumentation locations for BAe HS 748 aircraft [1] . 25
Figure 4 – Instrumentation locations for Lockheed C130 Aircraft Islander [1] . 25
Figure 5 – Comparison of relative overall rms severities for different aircrafts [1] . 26
Figure 6 – Comparison of relative overall rms severities for various flight conditions [1] . 27
Figure 7 – Comparison of relative overall rms severities for various locations [1] . 28
Figure 8 – Typical cruise vibration spectrum for Britten-Norman Islander aircraft [1] . 29
Figure 9 – Typical cruise vibration spectrum for BAe Jetstream aircraft [1]. 29
Figure 10 – Typical cruise vibration spectrum for BAe HS 748 aircraft [1] . 30
Figure 11 – Typical cruise vibration spectrum for Lockheed C130 aircraft [1] . 30
Figure 12 – Britten-Norman Islander vibration at cabin during cruise [2] . 31
Figure 13 – Britten-Norman Islander vibration at plane of propeller during take-off [2] . 32
Figure 14 – Britten-Norman Islander vibration at middle of fuselage during take-off [2] . 32
Figure 15 – Britten-Norman Islander vibration at middle of fuselage during cruise [2] . 33
Figure 16 – Britten-Norman Islander vibration at rear of fuselage during cruise [2] . 33
Figure 17 – Comparison of vibration severities for Lockheed C130 – Take-off [3] . 34
Figure 18 – Comparison of vibration severities for Lockheed C130 – Climb [3]. 34

Figure 19 – Comparison of vibration severities for Lockheed C130 – Cruise [3] . 35
Figure 20 – Comparison of vibration severities for Lockheed C130 – Reverse thrust [3] . 35
Figure 21 – Comparison of vibration severities for Lockheed C130 at blade passing
frequency [3] . 36
Figure 22 – Comparison of vibration severities for Lockheed C130 background random
overall rms [3] . 37
Figure 23 – Lockheed C130 vibration at forward fuselage during take-off – Flight 3 [3] . 40
Figure 24 – Lockheed C130 vibration at forward fuselage (Frame 257) during cruise –
Flight 3 [3] . 40
Figure 25 – Lockheed C130 vibration at forward fuselage (Frame 317) during cruise –
Flight 3 [3] . 41
Figure 26 – Lockheed C130 vibration at aft fuselage during cruise – Flight 3 [3] . 41
Figure 27 – Lockheed C130 vibration at forward fuselage during landing – Flight 3 [3] . 42
Figure 28 – Lockheed C130 vibration at forward fuselage during take-off – Flight 4 [3] . 42
Figure 29 – Lockheed C130 vibration at plane of propeller during take-off – Flight 4 [3] . 43
Figure 30 – Lockheed C130 vibration at plane of propeller during climb – Flight 4 [3] . 43
Figure 31 – Lockheed C130 vibration at plane of propeller during cruise – Flight 4 [3] . 44
Figure 32 – Lockheed C130 vibration at plane of propeller during landing – Flight 4 [3] . 44
Figure 33 – Landing shocks from Lockheed C130 vertical [4] . 45
Figure 34 – Landing shocks from Lockheed C130 lateral [4] . 45
Figure 35 – Landing shocks from Lockheed C130 longitudinal [4] . 46
Figure 36 – Transall C160 vibration at fuselage floor during take-off [7] . 47
Figure 37 – Transall C160 vibration at fuselage floor during cruise [7] . 47
Figure 38 – Transall C160 vibration at fuselage floor during landing [7] . 48
Figure 39 – Lockheed C130J variant vibration at plane of propeller during cruise . 48
Figure 40 – Airbus A400M vibration on fuselage floor during cruise conditions . 49
Figure 41 – IEC 60721-3-2 [13] – Stationary vibration random severities . 49
Figure 42 – IEC TR 60721-4-2 [14] – Stationary vibration random severities . 50
Figure 43 – IEC 60721-3-2 [13] – Stationary vibration sinusoidal severities . 50
Figure 44 – IEC TR 60721-4-2 [14] – Stationary vibration sinusoidal severities . 51
Figure 45 – IEC 60721-3-2 [13] – Shock severities . 51
Figure 46 – IEC TR 60721-4-2 [14] – Shock severities for IEC 60068-2-29 [17] test
procedure . 52
Figure 47 – IEC TR 60721-4-2 [14] – Shock severities for IEC 60068-2-27 [15] test
procedure . 52
Figure 48 – Comparison of four propeller aircraft vibrations [1] with IEC 60721-3-2 [13] . 53
Figure 49 – Comparison of Britten-Norman Islander aircraft vibrations [1] with
IEC 60721-3-2 [13] . 53
Figure 50 – Comparison of Lockheed C130 aircraft vibrations [3] with IEC 60721-3-2 [13] . 54
Figure 51 – Comparison of Transall C160 aircraft vibrations [7] with IEC 60721-3-2 [13] . 54
Figure 52 – Comparison of Britten-Norman Islander aircraft cruise vibrations [1] with
IEC 60721-3-2 [13] . 55
Figure 53 – Comparison of Britten-Norman Islander aircraft take-off/landing vibrations
[1] with IEC 60721-3-2 [13] . 55
Figure 54 – Comparison of Lockheed C130 aircraft cruise vibrations [3] with
IEC 60721-3-2 [13] . 56

– 4 – IEC TR 62131-6:2017 © IEC 2017
Figure 55 – Comparison of Lockheed C130 aircraft take-off/ landing vibrations [3] with
IEC 60721-3-2 [13] . 56
Figure 56 – Comparison of Lockheed C130J variant cruise vibrations with
IEC 60721-3-2 [13] . 57
Figure 57 – Comparison of Airbus A400M cruise vibrations with IEC 60721-3-2 [13] . 57
Figure 58 – Comparison of Lockheed C130 landing shocks [4] with IEC 60721-3-2 [13] . 58

Table 1 – Record durations and error estimates for measured data for Britten-Norman
Islander aircraft flight measurements . 9
Table 2 – Record durations and error estimates for measured data for Lockheed C130
flight vibration measurements . 11
Table 3 – Overall rms severities for Britten-Norman Islander [2] . 31
Table 4 – Overall rms severities for Lockheed C130 – Flight 3 [3] . 38
Table 5 – Overall rms severities for Lockheed C130 – Flight 4 [3] . 39
Table 6 – Overall rms severities for Transall C160 [7] . 46

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ENVIRONMENTAL CONDITIONS –
VIBRATION AND SHOCK OF ELECTROTECHNICAL EQUIPMENT –

Part 6: Transportation by propeller aircraft

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a Technical Report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 62131-6, which is a Technical Report, has been prepared by IEC technical committee
104: Environmental conditions, classification and methods of test.

– 6 – IEC TR 62131-6:2017 © IEC 2017
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
104/687A/DTR 104/744/RVDTR
Full information on the voting for the approval of this Technical Report can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62131 series, published under the general title Environmental
conditions – Vibration and shock of electrotechnical equipment, can be found on the IEC
website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
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ENVIRONMENTAL CONDITIONS –
VIBRATION AND SHOCK OF ELECTROTECHNICAL EQUIPMENT –

Part 6: Transportation by propeller aircraft

1 Scope
This part of IEC 62131 reviews the available dynamic data relating to the transportation of
electrotechnical equipment. The intent is that from all the available data an environmental
description will be generated and compared to that set out in IEC 60721 (all parts)[11] .
For each of the sources identified the quality of the data is reviewed and checked for self
consistency. The process used to undertake this check of data quality and that used to
intrinsically categorize the various data sources is set out in IEC TR 62131-1[18].
This document primarily addresses data extracted from a number of different sources for
which reasonable confidence exist in its quality and validity. The report also reviews some
data for which the quality and validity cannot realistically be verified. These data are included
to facilitate validation of information from other sources. The document clearly indicates when
utilizing information in this latter category.
This document addresses data from a number of data gathering exercises. The quantity and
quality of data in these exercises varies considerably as does the range of conditions
encompassed.
Not all of the data reviewed were made available in electronic form. To permit comparison to
be made, in this assessment, a quantity of the original (non-electronic) data has been
manually digitized.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
___________
References in square brackets refer to the Bibliography.

– 8 – IEC TR 62131-6:2017 © IEC 2017
4 Data source and quality
4.1 Vibration survey of four different propeller driven aircraft
Work was undertaken in 1989 to compare the source vibration on four different propeller
driven aircraft (see [1]). This comparison work was undertaken to establish base data for a
guidance chapter on propeller aircraft vibrations.
The four aircraft types encompassed by the vibration survey were: Britten-Norman Islander,
BAe Jet Stream 100, BAe HS 748 and the Lockheed (Hercules) C130 . The data from the first
three aircraft types were specifically collected for this comparison exercise during 1988.
However, the data for the Lockheed C130 originates from several flights undertaken for
another purpose during 1985. This Lockheed C130 data has commonality with other data
referred to in this document. Information on each of the four aircraft is set out below:
– The Britten-Norman Islander is a lightweight twin engine aircraft fitted with reciprocating
engines driving twin-bladed variable pitch propellers. With this arrangement different
power settings can be achieved by varying both engine speed and propeller pitch. The
general arrangement of the aircraft is shown in Figure 1.
– The BAe Jetstream 100 is a light utility transport aircraft fitted with twin, constant speed
turbo-prop engines each driving a three bladed variable pitch propeller. With a fixed shaft
rotational frequency of approximately 30 Hz, the blade passing frequency (shaft speed
times the number of propeller blades) for this aircraft is fixed at approximately 90 Hz. The
general arrangement of the aircraft is shown in Figure 2.
– The BAe HS 748 is a regional transport aircraft driven by twin turbo-prop engines fitted
with four bladed variable pitch propellers. As the engines are variable speed, different
power settings can be achieved by varying both engine speed and propeller pitch. For
cruise conditions the propeller shaft rotational frequency is typically around 22 Hz, giving
a blade passing frequency of around 88 Hz. The general arrangement of the aircraft is
shown in Figure 3. This particular aircraft was fitted in a fire fighting configuration and this
could be expected to give rise to increased vibration due to the presence of the large
water tanks located externally under the fuselage.
– The Lockheed C130 Mk 1 aircraft, encompassed by this exercise, is a large transport
aircraft driven by four fixed speed turbo-prop engines each powering a four bladed
variable pitch propeller. The propeller shaft rotational speed is approximately 17 Hz
producing a blade passing frequency of approximately 68 Hz. The general arrangement of
the aircraft is shown in Figure 4.
The measurements on all four aircrafts used the same flight instrumentation. This comprised
twelve piezo-electric accelerometers and associated charge amplifiers. The vibration
measurements were recorded on a 14 channel FM recorder. The system provided an effective
measurement frequency range of 4 Hz to 2 500 Hz. The accelerometers were arranged in four
tri-axial groups placed in the forward, centre and aft regions of the aircraft. The fourth
transducer group was placed in the plane of the propeller disc. All the transducers were
internally mounted on relatively stiff airframe locations.
Measurements were made for extended periods during the flight; the periods encompassed
take-off, climb, cruise, descent, landing and taxi. The take-off phase included bringing the
engines to full power, immediately before it started the take-off run. The landing phase
included the use of reverse thrust, if that was appropriate. All the take-off and landings
occurred on paved concrete runways of good length. That is no short take-off or landing
conditions were considered.
___________
Britten-Norman Islander, BAe Jet Stream 100, BAe HS 748 and Lockheed (Hercules) C130 are the trade names
of products supplied by Britten-Norman, BAE Systems and Lockheed Martin respectively. This information is
given for the convenience of users of this document and does not constitute an endorsement by IEC of the
products named.
The original analysis was mostly in the form of acceleration power spectral densities (PSDs),
although very few of these are presented in the report. The report does not indicate the record
duration used for the power spectral density analysis, but durations used by the agency, who
made these measurements, are typically better than 30 s. The analysis frequency bandwidth
was typically a little under 3 Hz. Whilst this is adequate to describe the broadband
background vibration induced by propeller aircraft, it is inadequate to quantify, in terms of
power spectral density amplitude, the tones arising from the propeller shaft, the blade passing
frequency and the associated harmonics. The report indicates that peak hold spectra were
used to estimate amplitudes at rotor and blade passing frequencies. However, the usual
approach used by this measurement agency, in such circumstances, was to compute the tonal
component root mean square (rms) by integration of the power spectral density amplitudes for
each tonal component. The method used to quantify the vibration amplitudes at the propeller
shaft, blade passing frequency and their harmonics, is a particular data analysis issue
encountered when addressing propeller aircraft vibration data.
The report compares relative severities of the four aircraft in terms of overall rms for the
different aircraft (Figure 5), flight conditions (Figure 6) and location within the aircraft (Figure
7). All these comparisons are in terms of relative amplitude i.e. they are all scaled such that
the largest amplitude is to unity. The report also presents typical cruise power spectral
densities for each aircraft type (Figure 8 to Figure 11).
Although the information in this document is limited, the quality of the information is
reasonable and meets the required validation criteria for data quality (single data item).
4.2 Britten-Norman Islander aircraft flight measurements
Work was undertaken in 1988 to establish the vibration severities of a Britten-Norman
Islander aircraft. The data from this measurement exercise was used within the comparison of
the previous data set. This document contains analysis of the entire measured data.
The measurement locations are as set out in the review of the previous data set and shown in
Figure 1 viz. tri-axial accelerometers on the floor of the cockpit, on the floor of the fuselage in
the plane of the propeller, on the floor in the centre of the fuselage and on the floor at the aft
fuselage. The flight conditions during which measurements were made comprised: take-off,
climb, left turn, long left turn at cruise speed and at an altitude of 500 ft (152 m), straight and
level at cruise speed at an altitude of 500 ft (152 m), descent and landing approach and
landing.
The data is presented in the form of acceleration power spectral densities (PSDs) for each
accelerometer at each of the seven flight conditions (84 plots in total). The report indicates
the record duration used for each power spectral density analysis and analysis frequency
bandwidth utilized, which are tabulated below (see Table 1).
Table 1 – Record durations and error estimates for measured data
for Britten-Norman Islander aircraft flight measurements
Flight event Analysis Measurement Random error
frequency duration
bandwidth
Hz s %
Take-off 3,014 30 10
Climb 3,014 35 9,7
Left turn 3,014 60 7,4
Long left turn at cruise speed and 500 ft 3,014 75 6,6
Straight and level at cruise speed at 500 ft 3,014 175 4,3
Landing approach 3,014 30 10
Landing 3,014 15 15
– 10 – IEC TR 62131-6:2017 © IEC 2017
The report does not separately quantify the tones arising from the propeller shaft, blade
passing frequency or the associated harmonics tones. Although these are clearly identified in
the analysis, the frequency they occur at is not fixed as the engine speed and propeller shaft
speed varies.
The overall root mean square values (3 Hz to 2 000 Hz) for each accelerometer at each of the
seven flight conditions are presented in Table 3. Selected power spectral densities are
presented in Figure 12 to Figure 16. Inspection of the power spectral densities presented in
the report indicates that the events have a spectral characteristic which would be expected
from variable speed engine propeller aircraft. That is, the shaft and blade passing
components occur at different centre frequencies for different flight conditions. With that said,
the landing measurements indicate unusual characteristics, which do not appear to represent
vibration conditions (they are more representative of shock conditions). For that reason the
power spectral density for the landing event are not included here. The landing approach
measurements are included as they mostly appear to be composed of vibration. However, the
shape of the power spectral density is not entirely consistent with the other flight conditions.
The report only presents analysed data in the form of acceleration power spectral densities.
The majority of these appear to have characteristics that would be expected from propeller
aircraft. However, this is not the case for the information for the landing event. With this
caveat the quality of the information is reasonable and meets the required validation criteria
for data quality (single data item).
4.3 Lockheed C130 flight vibration measurements
This large transport aircraft is extensively used in military and civil transport applications and
has been in-service for over four decades. The majority of the C130 aircraft fleet is used to
transport cargo and can be considered to put utility above passenger comfort. As such the
vibrations are generally at a level which would be unacceptable to the majority of civilian
passengers. The vibration characteristics and severities from this aircraft are those used by a
variety of international and national standards, to set the vibration test requirements for
propeller aircraft equipment. As a consequence it is not surprising that, over the years, a
variety of vibration measurement exercises have been undertaken on the aircraft. Although
several measurement exercises on the C130 were considered for this work, the majority of the
data presented are from measurement work undertaken by one agency. That work
encompassed measurements undertaken over several decades on a number of different
airframes and aircraft build standards. The measurement work reported was specifically
undertaken to establish the source vibration on the fleet of the Lockheed C130 aircraft
operated by the UK military forces (see [3]). This work was undertaken specifically to
establish payload cabin floor vibration data for use in establishing test severities for the UK
military standard relating to environmental testing requirements.
The various Lockheed C130 aircraft, encompassed by this exercise, were all UK military
aircraft used for a variety of roles, including peace keeping and disaster relief operations. The
general arrangement of the aircraft is shown in Figure 4. The vast majority of the worldwide
fleet of C130 aircraft (and all the C130 aircraft encompassed by this document), utilize a four
bladed straight propeller with a shaft rotational speed of approximately 17 Hz. This results in
a characteristic blade passing frequency of 68 Hz. However, a recent variant of this aircraft
replaced the four bladed straight propellers with six bladed propellers of a curved design. This
results in a blade passing frequency of 102 Hz.
The various measurement exercises reported here for the C130, used essentially the same
measurement locations and essentially the same flight instrumentation. The measurement
instrumentation comprised 12 piezo-electric accelerometers and associated charge amplifiers
which were recorded on an FM analogue recorder. The system provided an effective
measurement frequency range of 4 Hz to 2 500 Hz. The accelerometers were arranged mostly
in tri-axial groups placed in the cargo bay of the aircraft. In some cases axial (aircraft fore/aft)
measurements were omitted. All the transducers were internally mounted on relatively stiff
airframe locations, usually at aircraft frame locations.

In some of the flights reported here, additional measurements were made on two large
containers with the transducers located on the pallet adjacent to the container/floor interface
(i.e. as far as practicable measuring the vibration inputs to the containers). The two
containers were over 2 000 kg in mass and approximately 1,5 m wide and 3,0 m long. They
were positioned one behind the other in the aircraft cargo bay, together occupying the
majority of the central zone of the aircraft. The two measurement locations were positioned at
the aft port location of the aft container and the forward starboard location of the forward
container. As such the measurements spanned the total length of the two containers. For
these more recent measurements the FM analogue recorder was replaced with a digital
recorder.
Measurements were made for statistically reasonable periods, generally in excess of 30 s,
during the flight and encompassed take-off, climb, cruise, descent, landing and taxi. The
take-off phase included the period necessary to bring the engines to full power immediately
before the start of the take-off run. The landing phase included the use of reverse thrust. All
the take-off and landings measured were on adequate length good quality concrete paved
runways.
The analysis was mostly in the form of acceleration power spectral densities (PSDs), although
a certain amount of peak hold analysis was also undertaken. The data reports include a
statement of the measurement record duration and bandwidth for the power spectral density
analysis. As such, random error can be established for each analysis and the appropriate
values are shown in Table 2.
Table 2 – Record durations and error estimates for measured data
for Lockheed C130 flight vibration measurements
Flight 3 event Duration Random Flight 4 event Duration Random
error error
s % s %
Pre-flight taxi 30 11 Full power run 10 18
Take-off 30 11 Take-off 20 13
Climb 60 8 Climb 80 7
Cruise and turns 40 9 Cruise 60 8
Descent 40 9 Descent 160 5
Landing approach 40 9 Landing approach 60 8
Landing 30 11 Landing 20 13
The analysis frequency bandwidth was typically a little under 3 Hz. This is adequate to
describe the broadband background vibration induced by propeller aircraft. However, this
analysis bandwidth is not really adequate to quantify the tones arising from the propeller
shaft, blade passing frequency and the associated harmonics. In this case peak hold spectra
were used to give a more reliable estimate of the amplitudes at the blade passing tones
during transitory conditions. Specifically, the amplitudes of the tonal peaks were quantified
from the peak hold values by assuming they represent sinusoidal tones in the analysis
bandwidth. Provided the tones remain stationary in a single analysis band, the derived tonal
values accurately represent the largest value occurring over the duration of the record,
averaged over blocks of approximately 0,4 s duration.
Figure 17 to Figure 20 compare the tonal peak amplitudes for the vibration components at
engine shaft frequency, first propeller blade passing frequency and the subsequent two
harmonics of blade passing frequency. These comparisons are made for three locations
(forward, middle and aft) of the cargo bay and are presented separately for take-off, climb,
cruise and landing (specifically the use of reverse thrust). Figure 21 shows the peak tonal
value for the blade passing frequency for a range of flight conditions for which measurements
are available. Figure 22 shows similar information but for the overall vibration root mean
square acquired between 3 Hz and 2 000 Hz. Figure 23 to Figure 32 present selected

– 12 – IEC TR 62131-6:2017 © IEC 2017
acceleration power spectral densities for different locations and flight conditions from two
flights (designated here flights 3 and 4). These two flights used different, but overlapping,
measurement locations. Table 4 and Table 5 show the actual overall vibration root mean
square values from these two flights for all measurement locations and flight conditions for
which data are available.
The information in this document has some limitations but it does encompass the main cargo
hold of the Lockheed C130 aircraft. The quality of the information is reasonable and meets the
required validation criteria for data quality (single data item).
4.4 Lockheed C130 landing shock measurements
Work undertaken in 1988 reviewed landing shock measurements from four flights of a
Lockheed C130 aircraft (see [4]). This work was primarily undertaken to establish cabin floor
shock severities for the UK military standard relating to environmental testing requirements.
The measurement exercise included both normal and short landings. The latter were included
because this propeller aircraft is able to use short and temporary runways at remote locations.
The landing shocks arising from such use is typically more severe than would be the case for
normal landings. Indeed this measurement exercise arose partly because a payload carried
by a C130 aircraft (and some of the aircraft equipment) had been damaged as a result of a
short landing on a temporary runway during disaster relief activities.
The Lockheed C130 Mk 1 aircraft, encompassed by this exercise, is that utilized and
described in 4.3. The measurements used flight instrumentation comprising six piezo-electric
accelerometers and associated charge amplifiers which were recorded on a 14 channel FM
recorder. The system provided an effective measurement frequency range of 2 Hz to 250 Hz
with a subsequent acquisition rate of 1 000 sample per second (sps). The accelerometers
were arranged in two tri-axial groups; one placed at aft port location of one container, the
other at forward starboard location of a second container (see 4.3 for specific information on
the containers). Measurements were made throughout the landing phase with the touch down
event specifically extracted for shock analysis.
The analysis was in the form of time histories (which are not suitable for reproduction here)
and shock response spectra (SRS). The time histories used for the shock response spectrum
calculations were of approximately 1 s duration and adopted a resonant gain (Q) of 16,66 to
facilitate comparison with some historic US data.
The report contains time history and the shock response spectra from four flights,
five landings and from the six measurement channels. Within these data, the third flight
contained one tactical landing and one normal landing. The remaining flights were all normal
landings. Figure 33 to Figure 35 show the shock response spectra from all four flights for the
aircraft vertical, lateral and longitudinal axes.
Although the information in this document is limited in quantity and frequency range, the
quality of the information is reasonable and meets the required validation criteria for data
quality (single data item).
4.5 Supplementary data
The supplementary data, detailed below, comprises information arising from reputable
sources, but for which the data quality could not be adequately verified.
The SRETS study (see [5]) was undertaken during 1998 and reviewed both measured data
sources and test severities for a variety of methods of transportation. It compared two
measured data sets related to propeller aircraft. One of those data sets is from the UK
defence standard DEF STAN 00-35 [6], but that data set is already included in this document.
The second data set was from the French military standard GAM-EG-13 [7]. That standard

includes information from the Transall C-160 aircraft. The Transall C-160 is a heavy
transport aircraft (approximately 50 000 kg) powered by two turboprop engines each driving a
four-bladed propeller. The measured information included in GAM-EG-13 relates to two
ground and seven flight conditions. The measurements are from only one fuselage floor
location and the specific location is not stated. The measured information is presented in the
form of acceleration power spectral densities for take-off, cruise and landing, which are
included here as Figure 36, Figure 37 and Figure 38 respectively. Overall root mean square
vibration severities are also presented, listed here in Table 6, and are assumed to be over the
frequency range 1 Hz to 1 500 Hz. These overall root mean square values are lower than for
the other aircraft included in this document, but not unreasonably so. The power spectral
densities indicate that the blade passing tone is dominant and the frequency of the tone
appears to vary between 45 Hz to 55 Hz.
As part of an exercise, in the early 1970’s, to authenticate test severities for the US military
specification MIL STD 810[23], J.T. Foley [8] at the US Sandia National Laboratories
undertook an extensive exercise to establish transportation severities on a number of
platforms including two propeller aircraft i.e. the Lockheed C130 and the (now obsolete)
Douglas C133. Unfortunately, the analysis process used by Foley throughout his work is
relatively unique and not directly comparable with the information presented in this document.
Nevertheless, the information generated by Foley seems to be largely consistent with that
already reviewed in this document.
As already indicated a number of test standards adopt a shaped random profile, which seem
to be mostly based upon the vibration characteristics of the Lockheed C130. One standard
that differ
...