SIST EN 4888:2024

SLOVENSKI STANDARD
01-november-2024
Aeronavtika - Potniški sedeži v komercialnih letalih - Preskušanje zanesljivosti
Aerospace Series - Commercial aircraft passenger seats - Reliability testing
Luft- und Raumfahrt - Fluggastsitze für die zivile Luftfahrt - Zuverlässigkeitstests
Série aérospatiale - Sièges passagers d’avions commerciaux - Essais de fiabilité
Ta slovenski standard je istoveten z: EN 4888:2024
ICS:
49.095 Oprema za potnike in Passenger and cabin
oprema kabin equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 4888
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2024
EUROPÄISCHE NORM
ICS 49.095
English Version
Aerospace Series - Commercial aircraft passenger seats -
Reliability testing
Série aérospatiale - Sièges passagers d'aéronefs Luft- und Raumfahrt - Fluggastsitze für die zivile
commerciaux - Essais de fiabilité Luftfahrt - Zuverlässigkeitsprüfung
This European Standard was approved by CEN on 22 April 2024.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 4888:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 5
Introduction . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Abbreviated terms . 7
5 Reliability testing of aircraft sub-seat components . 8
5.1 Failure behaviour . 8
5.2 Reliability characteristics and their conversion . 8
5.3 Aspect test cycle time versus flight time and range . 9
5.4 Determination of reliability characteristics . 10
5.5 Degradation . 13
6 General test conditions . 13
6.1 General. 13
6.2 ATD . 13
6.3 Loading devices . 15
6.3.1 Loading device for applied loads. 15
6.3.2 Loading device for impact . 15
6.3.3 Loading device for literature pockets . 16
6.3.4 Loading device for backrest . 16
6.3.5 Loading device for seat pan . 17
7 Reliability testing of backrest . 18
7.1 Test requirements . 18
7.2 Test procedure . 20
7.2.1 General. 20
7.2.2 Test procedure for load case A. 20
7.2.3 General note for test procedure for load case B to H . 21
7.2.4 Test procedure for load case B. 21
7.2.5 Test procedure for load case C and D . 22
7.2.6 Test procedure for load case E . 23
7.2.7 Test procedure for load case F . 24
7.2.8 Test procedure for load case G . 25
7.2.9 Test procedure for load case H . 26
7.3 Failure criteria . 27
8 Reliability testing of moveable headrest . 28
8.1 Test requirements . 28
8.2 Test procedure . 29
8.2.1 Test procedure for load case A . 29
8.2.2 Test procedure for load case B . 30
8.2.3 Test procedure for load case C . 31
8.2.4 Test procedure for load case D1 and D2 . 31
8.2.5 Test procedure for load case E . 33
8.2.6 Test procedure for load case F . 33
8.3 Failure criteria . 34
9 Reliability testing of armrest. 34
9.1 Test requirements . 34
9.2 Test procedure . 36
9.2.1 Test procedure for load case A . 36
9.2.2 Test procedure for load case B . 36
9.2.3 Test procedure for load case C . 37
9.2.4 Test procedure for load case D . 38
9.2.5 Test procedure for load case E . 39
9.2.6 Test procedure for load case F . 39
9.2.7 Test procedure for load case G . 40
9.2.8 Test procedure for load case H . 40
9.2.9 Test procedure for load case I . 41
9.2.10 Test procedure for load case J . 42
9.3 Failure criteria . 43
10 Reliability testing of table . 44
10.1 Test requirements . 44
10.2 Test procedure . 45
10.2.1 General . 45
10.2.2 Test procedure for load case C . 47
10.2.3 Test procedure for load case D . 48
10.3 Failure criteria . 49
11 Reliability testing of literature pocket . 49
11.1 Test requirements . 49
11.2 Test procedure . 50
11.2.1 Test procedure for load case A . 50
11.2.2 Test procedure for load case B. 51
11.3 Failure criteria . 51
Annex A (informative) Random failure behaviour rate . 53
Bibliography . 54

European foreword
This document (EN 4888:2024) has been prepared by the ASD-STAN.
After enquiries and votes carried out in accordance with the rules of this Association, this document has
received the approval of the National Associations and the Official Services of the member countries of
ASD-STAN, prior to its presentation to CEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2025, and conflicting national standards shall
be withdrawn at the latest by March 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Introduction
A well-organized reliability management process is very important for manufacturers in order to
achieve the reliability requirements set by the customers and to continuously maintain market position.
The prediction of the failure behaviour of a product in the field should be accomplished as early as
possible. An optimized reliability management process contains qualitative and quantitative reliability
methods based on fatigue damage calculations, test data, condition monitoring, field failure data and
warranty cost analysis, which have to be fused to a closed loop failure analysis system in order to
consider all lessons learned in the analysis tools used in product development.
Customers expect a reasonably priced product, which has a high level of quality and reliability at the
same time.
The determination of the reliability of products is an essential component in the development and
manufacture of products. The reliability of these technical products describes the property of not failing
within a specified time period and to keep the failure rate at an acceptable level until the end of life in
given functional and ambient conditions.
The reliability and its characteristics are described via the confidence level and confidence range. An
important contribution concerns the analysis of service life information resulting from corresponding
tests or reported from the service by customers.
Reliability testing involves the definition, implementation and analysis of tests that are to represent the
use of seats in aircraft.
Furthermore, the second largest task of reliability testing involves analysing field data provided as
feedback from airlines. In this way, the data is validated based on previously conducted tests and
prognoses for future seat models are compiled.
1 Scope
This document specifies minimum reliability test requirements for sub-components of commercial
aircraft passenger seats. Test procedures including in-service load cases regarding passenger behaviour
for sub-seat components are specified. Abuse loads are excluded. This document is applicable to the
sub-seat components such as but not limited to backrest, headrest, armrest, table, literature pocket and
control elements.
This document does not apply to belts, Inflight-Entertainment, seat dress cover and cushions.
Additional environmental influences like temperature, radiation, gases and liquids may also alter the
reliability of the aircraft passenger seats and their sub-components over their lifetime but are not taken
into consideration in this document.
Tests on abrasion and surface durability are specified in EN 4860, EN 4864 and EN 4876.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 1728:2012/AC:2013, Furniture — Seating — Test methods for the determination of strength and
durability
SAE J826, Devices for Use in Defining and Measuring Vehicle Seating Accommodation
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
reliability
probability that a product will not fail during specified time period under given functional and
environmental conditions
4 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
A/C aircraft
ATD anthropomorphic testing device
CTR centre
DWD downward
Published by: SAE International (US) https://www.sae.org/.
FOLD-EXT fold extant
FC flight cycle
FH flight hour
FWD forward
LAP load attack point
LH left hand
LR long range flight
MTBF mean time between failure
MTBUR mean time between unexpected/unscheduled repair/removal
MTTF mean time to failure
RH right hand
RWD rearward
SR short range flight
SWD sideward
TTL taxi – take off – landing
UWD upward
5 Reliability testing of aircraft sub-seat components
5.1 Failure behaviour
The failure behaviour of a product is recorded by the reliability and is, additionally to the functional
properties, an essential criterion for the product assessment.
Decorative material is to be interpreted as a cosmetic addition to the substrate materials functionality.
During the tests, occurrence of defects will be separated in three different categories:
a) minor: defects or cosmetic findings, which have no or only a minor effect on the functionality of the
seat or a component and may be repaired or exchanged easily if necessary; depending on the
occurrence, these defects may be considered for the MTBF evaluation; test will be continued;
b) major: defects which have a direct effect on the functionality of the seat or a component; these
defects will be considered for the MTBF evaluation; test has to be stopped;
c) safety: defects which have a direct effect on the safety of an occupant, these defects will be
considered for the MTBF evaluation. The test shall be stopped and a safety evaluation shall be done.
5.2 Reliability characteristics and their conversion
The following reliability characteristics are usually taken as a basis from the customer viewpoint:
a) in case of non-maintainable units: mean time to failure (MTTF);
b) in case of maintainable units: mean time between failure (MTBF);
c) mean time between unexpected/unscheduled repair/removal (MTBUR).
These values are usually given in flight hours (FH) and shall be converted for the tests in the load
spectrum. Assuming that a load spectrum corresponds to the use of the component during a flight
cycle (FC), it is necessary to determine how many flight cycles an aircraft undergoes during the given
MTBF time in flight hours.
This results from multiplication of the requirement in flight hours by the ratio of flight cycles per flight
hour:
FC
day
MTBF = MTBF ⋅
Load collective FH
FH
day
(1)
where
MTBF is the mean time to failure load collective;
Load collective
MTBF is the mean time to failure in flight hour (h);
FH
FC is the flight cycle per day;
day
FH is the flight hour per day (h).
day
The MTBF values determined from tests are converted into flight hours by transposing the equation
according to MTBF :
FH
FH
day
MTBF = MTBF ⋅
FH Load collective
FC
day
(2)
where
MTBF is the mean time to failure per flight hour (h);
FH
MTBF is the mean time to failure load collective;
Load collective
FC is the flight cycle per day;
day
FH is the flight hour per day (h).
day
Failure and degradation parameters are specified in each individual testing criteria.
5.3 Aspect test cycle time versus flight time and range
To specify scenarios, representing the daily usage of aircraft sub-seat components, different types of
commercial aircraft shall be considered. Single aisle aircraft mainly used for short and medium-range
flights and twin aisle aircraft used for mid-, long- and ultra-long range flights. As the flight hours per
flight cycle ratio differs between these two categories of commercial aircraft, different load scenarios,
occurring during one flight (e.g. repetition of a specified load case per flight), shall be considered.
As a minimum utilization of the aircraft, the data from Table 1 shall be used for the transformation of
MTBF values from load collectives into flight hours and vice versa according to 5.2. Deviation from
these values shall be justified by statistical data.
Table 1 — Data for short range and long range
Type of flight mission Value
Short range
Average flight duration 1,5 h
Average daily utilization 8,5 h
Type of flight mission Value
Average flight cycles per day 5,8
Long range
Average flight duration 8,0 h
Average daily utilization 13,0 h
Average flight cycles per day 1,6

5.4 Determination of reliability characteristics
The systematic failure behaviour rate, i.e. failure rate shall be calculated according to Formula (3).
β−1
β t
 
λ(t) ⋅
 
TT
 
(3)
where
is the failure rate (per load collative);
λ t
()
T is the characteristic lifetime (number of load collectives);
t is the running time (number of load collectives);
β is the Weibull shape parameter.
The MTTF can be calculated according to Formula (4).
1
MTTF=T⋅+Γ 1

β

(4)
where
MTTF is the mean time to failure (number of load collectives);
T is the characteristic lifetime (number of load collectives);
t is the running time (number of load collectives);
β is the Weibull shape parameter;
Γ is the Gamma function.
=
If the characteristic lifetime T is unknown, it can be calculated according to Formula (5).
n β
β
 
t
i
T=
 
∑
x
i=1
 
(5)
where
T is the characteristic lifetime (number of load collectives);
ti is the running time of each test (number of load collectives);
β is the Weibull shape parameter;
x is the number of failures found;
n is the number of samples.
The MTTF can then be calculated according to Formula (6).
β
n
β
 t  
i
MTTF ⋅+ Γ 1

∑ 
x β
i=1 
(6)
where
MTTF is the mean time to failure (number of load collectives);
t is the running time for sample i (number of load collectives);
i
β is the Weibull shape parameter;
x is the number of failures found;
n is the number of samples;
Γ is the Gamma function.
Typical Weibull shape parameters for different materials are shown in Table 2 and shall be used.
Table 2 — Typical Weibull shape parameters
Weibull shape parameter
Material
β
Aluminium alloys (2024/3.1355), (7075/3.4365) 4,0
Titanium alloys (Ti6Al4V/3.7164) 3,0
Steel (R ≤ 1 655 MPa) 3,0
m
Steel (R > 1 655 MPa) 2,2
m
For other materials an estimation of the shape parameters should be compared to fixed values and if no
other proven data are available a conservative choice should be selected by using a Weibull shape
parameter of β ≥ 2,2.
The method in 5.4 is representing non-random failure behaviour and is therefore more accurate as the
simplified method shown in Annex A.
EXAMPLE 1 Five aluminium armrests (β = 4) of a long range seat were tested according to loads given in
Clause 8 until occurrence of a failure. The results of these 5 tests are shown in Table 3.
=
Table 3 — Example test results
Running time
Repetition Findings
(load collectives)
1 5 961
2 2 761
Armrest structure
3 3 301
cracked
4 4 536
5 3 305
4 44 4 4
5 961 + 2 761 ++3 301 4 536 + 3 305 1

MTTF ×Γ+=1 4 462×0,9064 4 044 load collectives
 
5 4


According to 5.2, 4 044 load collectives at a long range seat are representing a MTTF of 32 350 flight
hours.
It may happen, that after a reasonable time, no failure will be found and the test is stopped. In this case
the method above cannot be used for the evaluation.
If no failure is found, only statistical minimum values can be determined with the formulas below:
1
MTTF=T⋅+Γ 1
min min 
β

(7)
where
MTTF is the minimum mean time to failure (number of load collectives);
min
T is the characteristic lifetime (number of load collectives);
β is the Weibull shape parameter;
Γ is the Gamma function.
with
β

n
β
2∗ t
∑ i
i=1
T =
min
2
Χ
α

2 x+−1 ;1
( )
2
(8)
where
T is the minimum characteristic lifetime (number of load collectives);
min
t is the running time of each test (number of load collectives);
i
β is the Weibull shape parameter;
x is the number of failures found;
Χ is the Chi-Square distribution;

= =
α is the statistical level of significance (1 % to 99 %).
EXAMPLE 2 The armrest from the example above was improved and tested again. Each test was stopped after
6 000 load collectives equals 48 000 flight hours equals 10 years without any failure.

2× (6 000 ++++6 000 6 000 6 000 6 000 ) 1
 
MTTF × Γ 1 8 913 load collectives
min 
2
Χ 4

0,5

2 0+−1 ;1
( )
2
According to 5.2, 8 913 load collectives at a long range seat are representing a MTTF of 71 300 flight
min
hours.
5.5 Degradation
This document only covers mechanical wear and tear on new parts. Degradation due to environmental
influences e.g. chemical ageing of plastic parts is not part of the scope of this document and neither shall
it be applied on anything other than new parts.
6 General test conditions
6.1 General
All sub seat components should be tested with the pertinent seat. Any sub seat components not
pertinent to the relevant load paths do not need to be installed.
If the seat is used for the test, the seat shall be fixed via seat tracks or equivalent fixation to the test
bench.
Unless otherwise specified, the seat shall be stored in indoor ambient conditions for at least 24 h
immediately prior testing.
The test shall be carried out at indoor ambient conditions with a temperature of 23 °C ± 10 °C and
should be carried out with a relative humidity of 50 % ± 20 %.
Applied loading shall be maintained for at least 0,5 s.
After initial calibration of test equipment the equipment shall be kept in good working order to
maintain pertinent test results.
The following tolerances shall be used for the tests including the ATD in 6.2 and loading devices in 6.3:
a) forces: ± 1 % of the nominal force for 100 N and above; ± 5 % of the nominal force below 100 N;
b) velocities: 0 % to 5 % of the nominal velocity;
c) masses: ± 1 % of the nominal mass;
d) dimensions: ± 3 mm of the nominal dimensions;
e) angles: ± 2° of the nominal angle.
The speed for cycle testing shall not be higher than 3 600 cycles per hour.
6.2 ATD
An ATD according to SAE J826 shall be used for the following test in this document.
+==
The ATD device shall be representing the human body. Therefore, the dimensions and weights of the
different body parts shall be representative.
Table 4 shows the weight distribution for a standard Hybrid III crash test dummy and the 90 kg ATD
device which shall be used for testing. The values for the 90 kg test device are interpolated between the
77,7 kg (50 %il) and the 101,2 kg (95 %il) values.
Table 4 — Weight distribution for a standard Hybrid III crash test dummy and the 90 kg ATD
device
50 %il 90 kg ATD 95 %il
Body segments
kg kg kg
Head 4,54 4,75 4,94
Neck 1,54 1,61 1,68
Upper torso 17,19 19,85 22,27
Lower torso 23,04 26,84 30,3
Upper arm, left or right 2 2,42 2,81
Hands, left or right 0,57 0,57 0,57
Lower arms, left or right 1,7 1,89 2,06
Upper leg, left or right 5,99 7,15 8,21
Lower legs left or right 4,29 5,05 5,75
Feet, left or right 1,16 1,39 1,59
Sum 77,7 90,00 101,2
If some of the body parts are not existing (e.g. arms, hand, feet) or not separated (e.g. upper and lower
torso) the weights shall to be added to the parts where the missing parts are normally attached or two
parts have to be combined into one body part.
EXAMPLE The ATD according to SAE J826 has only upper body parts, a lower body part, lower and upper
legs and feet. So, the weight of the upper and lower torso has to be combined in the upper part and also the weight
of the head, neck, arms and hands have to be added to the weight of the combined upper and lower torso.
The weight shall be evenly distributed over all of the body parts.
For dimensions of the body parts refer to Figure 1.
Dimensions in mm
Figure 1 — Dimensions of ATD body parts
6.3 Loading devices
6.3.1 Loading device for applied loads
If possible a loading device according to Figure 2 should be used for the test in this document. The
loading device should consists of a circular rigid pad with a maximum diameter of 100 mm (edge radius
10 mm). It can be used together with a strap in some cases.
Dimensions in mm
Key
F force
Figure 2 — Loading device for applied loads
6.3.2 Loading device for impact
A 9 kg rigid jig specified in Figure 3 made of metal or plastic, of equal weight distribution with a
maximum radius of 20 mm at each edge shall be used.
Dimensions in mm
Key
a
Height depends of material to reach 9 kg.
Figure 3 — Loading device for impact load
6.3.3 Loading device for literature pockets
A loading device as specified in Figure 4 shall be used for testing of the lower literature pocket.
Dimensions in mm
Figure 4 — Loading device for literature pockets
6.3.4 Loading device for backrest
A loading device as specified in Figure 5, can be used instead of the ATD for testing of the backrest.
Dimensions in mm
Figure 5 — Loading device for backrest
EN 1728:2012/AC:2013, Figure 5 specified the loading device for backrest.
6.3.5 Loading device for seat pan
A loading device as specified in Figure 6 can be used instead of the ATD for testing of the seat pan. This
loading device shall be based on EN 1728:2012/AC:2013, Figure 3, but additional structures shall be
added, according to Figure 6. The additional structure shall be added to apply the force F2 at the same
position as the force F when using an ATD, see Figure 7.
Dimensions in mm
Key
F1 rear loading point
F front loading point
Figure 6 — Loading device for seat pan
7 Reliability testing of backrest
7.1 Test requirements
The reliability test of backrest shall be done according to Table 5. Table 6 shows load case in-service
representations. Figure 7 to Figure 14 illustrate the load cases.
Table 5 — Reliability test of backrest and kinematic
Repetition
per flight
Component Applied
cycle
Load case LAP
description loads
for
for SR
LR
Backrest and A Impact DWD Upper side, mid, mid 28 Ja 0,2 0,2
kinematic
Dummy upper torso: In 90 kg ATD +
B RWD TTL or alternative 50 N or 120 N 2 4
loading device without ATD
Front side/up both sides
C RWD 250 N 2 3
via a traverse: In TTL
Repetition
per flight
Component Applied
cycle
Load case LAP
description loads
for
for SR
LR
Front side/up both sides
D 250 N 1 2
via a traverse: In TTL
Front side/up both sides
E FWD 135 N 1 3
via a traverse: In TTL
F TTL-recline Dummy or alternative until full 1 4
TTL loading device recline
G DWD Dummy lap FWD edge or 90 kg ATD + 1 4
front edge of the seat pan 400 N or
cushion: In TTL or 600 N
alternative loading device without
ATD + 400 N
H RWD Front side/up aisle side 160 N 1 1
or opposite of seat lock:
In TTL
B1 RWD Dummy upper torso: In 90 kg ATD + 2 8
Full Recline or alternative 50 N or 250 N
loading device without ATD
C1 RWD Front side/up both sides 250 N 2 3
via a traverse: In Full
Recline
D1 Front side/up both sides 250 N 1 2
via a traverse: In Full
Recline
E1 FWD Front side/up both sides 135 N 1 3
via a traverse: In Full
Recline
G1 DWD Dummy lap FWD edge or 90 kg ATD + 2 5
front edge of the seat pan 400 N or
cushion: In Full Recline or 600 N
alternative loading device without
ATD + 400 N
H1 RWD Front side/up aisle side 160 N 1 2
or opposite of seat lock:
In Full Recline
a
The applied load is based on hand luggage weight of 9 kg.

Table 6 — Load case representation for backrest and kinematics
Load case In-service representation
A Placing hand luggage vehemently on top of the backrest.
B/B1 Sitting down in seat and moving during flight.
C/C1 Pulling fore-seat backward while standing up/sitting down.
D/D1 Pushing backrest backward while kneeling on seat.
E/E1 Leaning against fore seat.
F Putting seat into recline position and back to TTL.
G/G1 Sitting on FWD edge of seat bottom.
H/H1 Pulling fore-seat backwards while standing up with one hand on backrest.

7.2 Test procedure
7.2.1 General
The ATD shall be placed in the seat during all load cases. The ATD is only shown in the Figure 7,
Figure 9 and Figure 12, if the LAP is directly at the ATD. For all other load cases the ATD is not shown.
The seat belt shall be buckled up.
The load application points at the ATD that shall be used are shown in Figure 7.
Dimensions in mm
Key
F force
Figure 7 — Dimensions and LAP test dummy (ATD)
7.2.2 Test procedure for load case A
The rigid jig according to 6.3.2 shall fall freely onto the backrest in principle operating as shown in
Figure 8. The load application point is mid of upper edge of the backrest. Falling height shall be
calculated to reach a load of 28 J.
Figure 8 — Backrest load case A
7.2.3 General note for test procedure for load case B to H
Each load case, besides load case F, shall be applied in upright position according to Table 5 first.
Then, for short range A/C, backrest shall be set to full recline position according to load case F and load
cases B1 to H1 shall be applied according to Table 5. Following, backrest shall be set back to upright
position. Load case F is then also completed.
For long range A/C backrest shall be set to full recline position according to load case F and load cases
B1 to H1 shall be applied according to Table 5. Backrest shall then be set back to upright position.
Following load case F shall be repeated three more times.
7.2.4 Test procedure for load case B
As a loading device an ATD according to 6.2 or a backrest loading pad according to 6.3.4 can be used.
In case using an ATD, the upper torso of the ATD shall be pushed equally into the backrest surface
making full contact according to Figure 7 and Figure 9.
In case using an backrest loading pad a force of 120 N shall be applied at the centre line of the backrest
in a height of 450 mm + 97,6 mm measured from the intersection from the bottom cushion to the back
cushion with a loading device according to 6.3.4. The backrest loading pad should be oriented in a way
that the width of 250 mm is horizontal.
Key
F force 90 kg ATD + 50 N or 120 N without ATD
Figure 9 — Backrest load case B
7.2.5 Test procedure for load case C and D
The upper end of the backrest shall be moved into RWD direction parallel on both sides e.g. via a
traverse. Load application point shall not be lower than 5 cm from the upper end of the backrest
structure.
Key
F force 250 N
Figure 10 — Backrest load case C and D
7.2.6 Test procedure for load case E
The upper end of the backrest shall be moved into FWD direction parallel on both sides e.g. via a
traverse. Load application point shall not be lower than 5 cm from the upper end of the backrest
structure.
Key
F force 135 N
Figure 11 — Backrest load case E
7.2.7 Test procedure for load case F
As a loading device an ATD according to 6.2 or a backrest loading pad according to 6.3.4 can be used.
In case using an ATD, the upper torso of the ATD shall be pushed equally into the backrest surface
making full contact according to Figure 7 and Figure 12.
In case using a backrest loading pad the force shall be applied at the centre line of the backrest in a
height of 450 mm + 97,6 mm measured from the intersection from the bottom cushion to the back
cushion with a loading device according to 6.3.4. The backrest loading pad should be oriented in a way
that the width of 250 mm is horizontal.
If applicable the test procedure for load case F are the following steps:
a) the recline mechanism shall be activated;
b) the loading device shall be pushed RWD until the backrest is in full recline position according to
Figure 7;
c) the recline mechanism shall be disengaged;
d) the loading device shall be removed from the backrest;
e) the recline mechanism shall be activated until the backrest returns to the upright position;
f) the recline mechanism shall be disengaged.

Figure 12 — Backrest load case F
7.2.8 Test procedure for load case G
As a loading device an ATD according to 6.2 or a seat pan loading pad according to 6.3.5 can be used.
In case using an ATD, the load shall be applied equally to the front edge of the seat pan cushion. Load
transfer via lower legs into the floor shall be avoided, according to Figure 13 a).
In case using a seat pan loading pad, the loading pad shall be positioned in order to put the point F at
175 mm measured at the centre line of the seat place at the intersection from the bottom cushion to the
backrest cushion, according to Figure 13 b).
In this case, a load of 600 N shall applied on point F and additional load of 400 N on point F shall be
1 2
applied.
Dimensions in mm
a) with ATD b) with seat pan loading pad
Key
F force 90 kg ATD + 400 N
F1 force 600 N
F2 force 400 N
Figure 13 — Backrest load case G
7.2.9 Test procedure for load case H
The upper end of the backrest shall be moved into RWD direction on the opposite position of the seat
lock. Load application point shall not be lower than 5 cm from the upper end of the backrest structure.
Key
F force 160 N
Figure 14 — Backrest load case H
7.3 Failure criteria
Only findings of category b and c shall be used for statistical evaluation of the test results. For backrest
and kinematic these failures are:
a) minor:
1) loss of function but easily re-adjustable;
b) major:
1) total loss of function;
2) any structural damages;
3) any blocking point of any kind;
c) safety:
1) sharp edges;
2) blocking of egress path;
3) no securing of TTL position;
4) pinching hazards.
8 Reliability testing of moveable headrest
8.1 Test requirements
The reliability test of movable headrest shall be done according to Table 7. Table 8 shows load case in-
service representations. Figure 15 to Figure 21 illustrate the load cases.
If one of the following movable headrest options exists, all tests shall be done according to Table 7:
a) up/down;
b) tilt;
c) movable side wings.
Table 7 — Reliability test of headrest
Repetition per flight
Component Applied
cycle
Load case LAP
description loads
for SR for LR
Headrest A Impact Evenly distributed 28 J 0,2 0,2
over the headrest
DWD
upper edge
B RWD Front side, at the 250 N 2 6
centreline of the
upper edge
C FWD-RWD At the centreline of ±135 N
the headrest upper 2 6
edge.
Headrest D1 UWD-DWD At the centreline of Activation 2 5
the headrest load up
(slide)
(2 hands motion) to ± 135 N
at the
stops
D2 Load applied up to Activation
5 cm inside from load up
the wing edge to ± 75 N
at the
(1 hand motion)
stops
Headrest E FOLD-EXT Load applied up to Activation 1 5
5 cm inside from load up
Repetition per flight
Component Applied
cycle
Load case LAP
description loads
for SR for LR
(wings) the wing edge to ± 80 N
opposite the hinge. at
...