NBSIR 75-647

Mechanical Tests of FAA-E2491

Airport In-Pavement Approacli and

Thresliold Lights

Donald C. Robinson

Engineering Mechanics Section

Mechanics Division

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

January 1975

Final

Prepared for Federal Aviation Administration

Washington, D. C. 20590

NBSIR 75-647

MECHANICAL TESTS OF FAA-E-2491

AIRPORT IN-PAVEMENT APPROACH AND

THRESHOLD LIGHTS

Donald C. Robinson

Engineering Mechanics Section

Mechanics Division

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

January 1975

Final

Prepared for Federal Aviation Administration

Washington, D.C. 20590

U. S. DEPARTMENT OF COMMERCE. Frederick B. Dent. Secretary

NATIONAL BUREAU OF STANDARDS. Richard W. Roberts. Director

CONTENTS

Page

L. INTRODUCTION I

2. TEST SPECIMENS 2 2.1 Airport Marker Light Base 2 2.2 Approach and Threshold Lights 2

3. INSTRUMENTATION 3 3.1 Airport Marker Light Base 3

3.2 Optical Cover Assembly 3 3.3 Glass Prism 3

4. TEST PROCEDURES 4

4.1 Static Load Tests of Old Style Light 4

4.2 Static Load Tests of New Style Light 4

4.3 Static Load Tests of Instrumented New Style Light .... 5 4.4 Static Load Test of Instrumented Old Style Light .... 5 4.5 Impact Tests of New Style Light 5

5. TEST RESULTS 6

5.1 Static Load Tests 6

5.2 Impact Tests 6

6. DISCUSSION AND CONCLUSIONS 7

7. RECO^f^ENDATIONS 7

8. ACKNOWLEDGMENT 8

MECHANICAL TESTS OF FAA-E-2491 AIRPORT IN-PAVEMENT

APPROACH AND THRESHOLD LIGHTS

Donald C. Robinson

ABSTRACT

Static and impact load tests were performed on old and new styles of one manufacturer's design for

FAA-E-2491 airport in-pavement approach and threshold

lights which were mounted in light bases encased in

concrete. Static tests were conducted on five lights

using either a 6-inch diameter steel plate or a rubber

pad through which loads were applied to the center

of the light optical cover assembly. Drop tests were conducted on one light using a 5-lb steel ball which

was directed to impact at various locations on the

optical cover assembly. The old style lights were found

to comply with load requirements for the current specification. The maximum load sustained by both style lights

when loaded through a rubber pad was about two-thirds

of the maximum load sustained when loading directly

through the steel plate. A discussion is given of the

photometric measurements of the light beam displacement

measured during the load tests, the deflections and

strains of two new style lights measured under two

loading conditions and the test procedures for determining the performance of approach and threshold lights.

Key words: Airport approach and threshold lights, glass

prism, impact tests, light bases, optical cover assembly,

photometric measurements, static tests.

1. INTRODUCTION

Type FAA-E-2491 in-pavement approach and threshold lights have failed

in runways at airports which accommodate modern large aircraft such as the 747 and DC-10. The Federal Aviation Administration has suggested that some of the failures may be related to larger loads imposed by these "jumbo

jets" than the loads encountered during the development period for writing

the current specification. The majority of the light mechanical failures

have resulted in fracture of the glass prisms. However, other failures

are characterized by the prism being pushed into the optical cover assembly

with no glass fracture. The design of these lights which have failed in

service ("old style") was therefore changed by one manufacturer to a "new

style" in order to accommodate larger, but heretofore undetermined, service

loads

.

Subsequently, the Federal Aviation Administration requested that a series of mechanical tests be performed on two old style lights of the

I
type which have had a high failure rate and four of these new style lights,

all made by the same manufacturer. The objectives of this program were

(1) determine if the old style lights would meet the load bearing requirements for the existing specification, (2) evaluate the capability of the new

style lights to meet current specification requirements and (3) to obtain

data for possible revision of the specification to increase the load support

capabilities of the lights.

Static tests were conducted on the old and new style lights by applying

the loads directly through a 6-inch diameter steel plate, or through a rubber pad to simulate loading through a tire. In addition, impact tests

were conducted on a new style light by dropping a steel ball at various

locations on the light optical cover assembly.

' -2.' TEST SPECIMENS

2.1 Airport Marker Light Base

Type LB-4 airport marker light bases were used in the tests. Three

of these bases were each encased in a J-foot diameter by 3-foot deep concrete

cylinder in order to simulate a runway installation.--' The bases were cast

in the inverted position in order to insure intimate contact between the

base and concrete. Reinforcing steel was placed near the top surface of

the concrete in order to minimize cracks [ij.**

After the concrete hardened, 7/16-inch diameter threaded bolt holes were made in the flange at the top of the bases in order to install steel

adapter rings to which the light units were attached. The adapter rings

were installed according to procedures given in Reference 2 with one modification, which was approved by the Federal Aviation Administration. The latter

involved the use of a gypsum plaster having a bearing strength in excess

' of the base concrete strength, which was used between the base flange and

the adapter ring, and concrete grout for filling the void around the outer

edge of the ring.

2.2 Approach and Threshold Lights

Two old style approach and threshold lights, which were removed from

a runway, were furnished for testing. The top surface of the optical cover assembly above the prism for both of these lights appeared to be concave

and the prism for one of the units had been damaged. The prism had fractures

at each end and had rotated within the opening in the optical cover assembly

in which it was molded. The damaged unit was repaired prior to being tested

'-'''U.S. customary units of measurement have been used throughout this report.

Readers interested in making use of the coherent system of SI units will

find conversion factors in "ASTM Standard Metric Practice Guide" (Designation: E380-72) available from American Society for Testing and Materials,

1916 Race Street, Philadelphia, Pa., 19103.

^"Numbers in brackets indicate references given at the end of this report.

2
by an official from the manufacturer who installed and molded a new prism

in the cover assembly.

Four new style lights were furnished for testing. It was observed

that the top surface of the optical cover assembly for these lights above

the prism were all convex. Adapter rings and all bolts and lock washers

necessary for assembly were also supplied. All of the lights tested were produced by one manufacturer.

A schematic of a light unit installed in the LB-4 base encased in

a concrete cylinder is shown in Figure 1 and a photograph showing the ex- posed optical cover assembly and adapter ring for the installed light is

given in Figure 2.

3. INSTRUMENTATION

3,1 Airport Marker Light Base

During tests of airport marker light bases prior to development of

the adapter rings, failure modes had been generated in the base flange

and sidewall [3j. As a consequence of this experience, it was decided to

mount a strain gage to the LB-4 base flange and another to the base sidewall to measure the strain in the base during the static tests. These strains

proved to be quite small (600 x 10'^ or less) and no permanent deformation

occurred in the base during any of the static tests.

3.2 Optical Cover Assembly

The optical cover assembly casting was instrumented to determine the

strain at several locations and to measure its deflection during two static

load tests of the new style lights. Figure 3 shows the relative position

of the strain gages which were attached to the recessed area behind the

prism on the under side of the optical cover assembly. The casting surface was ground smooth and cleaned prior to installation of the gages.

In order to measure the deflection of the cover assembly, a small

hole was drilled and tapped in the center of the recessed area and a fixture was installed for later attachment to a displacement transducer. The

transducer chosen for this purpose was a direct current differential transformer (DCDT), having a sensitivity of 1.50 volts per inch. The DCDT coil

assembly was clamped to a bar whose magnetic base was secured to the base

of the LB-4 light base. The core was then attached to the fixture on the

optical cover assembly just prior to installing the light to the adapter

ring. It was necessary to remove the lower portion of the light unit in

order to provide for the above instrumentation of the cover assembly.

3.3 Glass Prism

The glass prism in the optical cover assembly was instrumented to

determine the strain during static load tests of one old style and two new style lights. Figure 3 shows the location of the strain gages for a static test. In addition, a small displacement range DCDT was mounted to

3
the under side of the optical cover assembly in order to measure deflection

of the prism during a static load test on one old style light. The transducer used for this purpose had a sensitivity of 6.02 volts per inch.

; : , ^ 4. TEST PROCEDURES

The static load tests were performed in a 400,000 Ibf capacity universal testing machine. The LB-4 light base encased in concrete was placed

on a 36-inch diameter by 0,75-inch piece of plywood to protect the machine

platen. All of the lights were installed in accordance with procedures

given in Reference 2. Static loads were applied using either a 6-inch diameter by 1^-inch thick steel plate or using a rubber pad having a Shore

A hardness of 55 to 65 through which the loads were transferred to the cover assembly. Figure 4 shows the set-up when using the 6-inch diameter

plate. When the rubber pad was employed, it was compressed by a large steel

plate which overlapped the top of the optical cover assembly, as shown

in Figure 5.

The signals from the strain gages and displacement transducer were

fed to signal conditioning equipment and the data were digitized and re- corded on a paper tape, using a multichannel data acquisition system.

4.1 Static Load Tests of Old Style Light

The old style light without obvious damage, Serial No. 267, was tested

to determine if it met the static load bearing requirements of Specification

FAA-E-2491a [4j. Static loads were applied to the center of the top of

the optical cover assembly through a 6-inch diameter by 1^-inch thick steel

plate. The load was applied at a rate of 20,000 Ibf per minute to a maximum

load of 80,000 Ibf, this load was maintained for 2 minutes, and then removed.

Since no failure was observed, a subsequent load test was conducted

at the request of the Federal Aviation Administration in which the load was applied at a rate of 20,000 Ibf per minute until failure occurred.

Photometric measurements were made before and after this test to determine

the light beam displacement.

4.2 Static Load Tests of New Style Light

Static load tests were conducted on a new style light. Serial No.

676, according to the test program given in Appendix A which was furnished

by the Federal Aviation Administration. Before the load test began, an initial photometric scan was made for a reference of the light output displacement. For this test, a rubber pad of Shore A hardness 55 to 65 was placed over the light and a flat steel plate which overlapped the top portion

of the optical cover assembly was placed over the pad. The load was applied

at a rate of 20,000 Ibf per minute to a load of 76,000 Ibf, this load was maintained for 5 minutes, and then removed. Photometric measurements were made after the load was removed to determine displacement of the light

beam. . .

.

4
After this test, in which no failure occurred, the rubber pad and

steel plate were removed and a 6-inch diameter by 1^-inch thick steel plate was centered over the light. Loads were applied to the light using this

test fixture at a rate of 20,000 Ibf per minute until failure occurred.

4.3 Static Load Tests of Instrumented New Style Light

A load test was conducted for a new style light, Serial No, 678, which

had been instrumented to measure strain at several locations and deflection at one location of the optical cover assembly. The load was applied

to the top center of the light through a 6-inch diameter by 1^-inch thick

steel plate, according to the test program in Appendix A. The load was applied at a rate of 20,000 Ibf per minute until failure occurred. The

strain and deflection data were recorded at load intervals of 10,000 Ibf,

A distributed load test was conducted for another new style light,

Serial No, 679, which was also instrumented to measure strain and deflection at the request of the Federal Aviation Administration. The test was conducted in the same manner as the load test for the Serial No. 678 new

style light with the same measurements, except that the load was applied

through a rubber pad to simulate loading through a tire.

4.4 Static Load Test of Instrumented Old Style Light

r A distributed load test was conducted for an old style light, Serial

No. 664. For this test, the glass prism was instrumented to record both

the strain and displacement at the center of the prism, since some runway

light failures had involved large prism motion. The load was applied at

a rate of 20,000 Ibf per minute in the same manner as the distributed load

(rubber pad) test for the Serial No, 679 new style light,

4,5 Impact Tests of New Style Light

Impact tests were conducted on a new style light. Serial No, 677,

according to the test program given in Appendix A, A complete light unit

was installed on the test light base, A 5-lb steel halt with a hardness

of Rockwell C66 was dropped through a 3,5-inch diameter metal tube whose

upper end was clamped to the moveable crosshead of a universal testing

machine, ^'^ The tube was first aligned directly over the center of the optical cover assembly and the ball was dropped from a height of 6-feet and

constrained after it rebounded from the surface of the cover assembly.

Since the light withstood the initial impact test, the position of the

tube was varied during subsequent drop tests so that the ball impacted

at five different locations on the top of the cover assembly. Each of these

locations was approximately ^-inch from the opening in the cover assembly

casting into which the glass prism v;as molded, i.e. the ball impacted the

metal directly above the prism. Figure 6 shows the impact test arrangement

which was set up in the same machine used for the static load tests,

*The Federal Aviation Administration approved the use of a harder ball

than indicated in the test program given in Appendix A.

5
5. TEST RESULTS

5,1 Static Load Tests

The principal results of the static load tests are summarized in Table

1. All of the tests on the new style lights were terminated when the glass

prism in the optical cover assembly fractured. These fractures all occurred

in the center of the prism, as shown in Figures 7a and 7b. The load versus deflection of the optical cover assembly measured when the lights were

loaded through the 6-Lnch diameter steel plate and through the rubber pad

is plotted in Figure 8. The strains measured on the cover assembly during

these tests are shown in Figures 9 and 10 and the strains measured on the

glass prism are plotted in Figure 11. The measured deflection and strain

levels at a given load were generally higher for the distributed load (rubber

pad) tests than for the concentrated load (steel plate) tests on the new

style lights. '

During the test on the old style light. Serial No. 267, when the load was applied to the optical cover assembly by a steel plate, the glass prism

was displaced from its initial position in the cover assembly and the test was terminated when the cover assembly casting fractured at a load of 316,500

Ibf. After this test, the paint was removed from the cover assembly and

dye penetrant was sprayed onto the fractured surface. Photographs of the

cracks were then taken when the cover assembly was exposed to an ultraviolet light source. Figure 12 shows the two principal fractures which

eminated from the topmost surface of the cover assembly and propagated

to the edge of the casting.

When static loads were applied to the repaired old style light. Serial

No. 664, through the rubber pad, the test was terminated when the glass

prism fractured. The recorded displacement data indicated that the prism

had moved outward about .040-inch prior to its fracture. This small amount

of motion could not have been determined by visual examination of the prism

after the test.

The photometric measurements of the displacement of the light beam

were taken during the static load tests of one new style and one old style

light. These measurements indicated an angular shift of approximately 0.090

degree during the maximum loads to which the lights were subjected and

approximately a 0.030 degree permanent shift from the initial setting following removal of the load. It is unknown how much of the displacement is

caused by "seating" of the fixture or the compaction of the test bed itself

under load rather than any actual change in the fixture proper. In any

case, the small shifts are considered insignificant for the approach light

application where relatively wide beams exist.

5.2 Impact Tests

Following each of the impact tests, the light was visually examined.

There was no evidence of breakage, fracture or deformation that could cause

leaks or shift the light output pattern. These tests were inconclusive

in that only one light of one style was tested and no damage occurred.

6
6. DISCUSSION AND CONCLUSIONS

The two old style lights which were tested complied with the load

bearing requirements for the current specification, which has a maximum

static load requ irement of 80,000 Ibf [4j. Three new style lights tested

also complied with the specified static load requirements. The old style

lights withstood larger compressive loads before failure than the new style

lights, whether the loads were applied through a steel plate or through

a rubber pad. This result suggests the possibility that factors which were

not measured could have influenced the maximum loads which were able to

be sustained. Such factors might be tolerances within the optical cover assembly prism opening, tolerances of the glass prism, and/or permanent

deformation or residual stresses within the cover assembly. It is not clear

from the tests conducted on the old style lights, both of which were removed

from runways and one of whose prisms had been obviously damaged, how the

load bearing requirements of the current specification should be revised.

It is necessary that some procedures be developed in order to determine

the magnitudes of various types of service loads to which the approach

and threshold lights are subjected in runways before meaningful bearing

loads can be specified. In this regard, it should be noted that the load

bearing tests in the current specification are inadequate for duplicating

some of the service failures which have been reported; namely, failures

where the glass prism is pushed into the optical cover assembly with no fracture occurring.

Both the old and new style lights when loaded through a rubber pad

failed at about two-thirds of the bearing load when compressed through

a steel plate. Analysis of the deflection and strain data measured for

the new style lights indicate that the test when the loads were applied

through a rubber pad was more severe than when the loads were applied directly through a steel plate. This observation is based on a small number

of tests for lights designed by one manufacturer.

The small shifts in the photometric measurements of the displacement

of the light beam are considered insignificant for the approach light application where relatively wide beams exist.

7. RECOMMENDATIONS

It is apparent from the results of the static and impact tests on

the airport marker lights that the tests conducted do not provide sufficient information on which to consider revisions of the bearing requirements

in the FAA approach light specification [4], Additional tasks required

in order to obtain data for basing such judgments include 1) detailed analyses of approach light service failures and 2) quantification of the service

loads experienced by the lights. It is therefore recommended that further

research be undertaken in order to develop techniques in the laboratory

for field recording and measuring of the critical dynamic service loads

""^The tests conducted indicate that old style lights which can withstand

twice the specified bearing load have still experienced service failures.

7
experienced by approach and tlireshold Lights. In order to demonstrate the

creditabil ity of such procedures, field measurements should be undertaken

to record and measure the service loads at one or two locations on a run- way where airport maintenance records reveal the most frequent incidence

of light failures due to mechanical loading have occurred. In addition,

consideration should be given to supplementing the load bearing tests in

the current specification with test procedures in which loads are applied

directly to the optical prism in order to simulate service failures in

which the prism is pushed into the optical cover assembly.

8. ACKNOWLEDGMENT

'

: .' The photometric measurements were taken during the mechanical tests

by Messrs. W. F. Mullis and M. R. Freund and subsequently analyzed by Mr.

Mullis. Instrumentation was provided by Messrs. J. L. Michalak and R. E.

Snyder. Photographic assistance was provided by N. Halscy.

8
REFERENCES

1. Davis, L. J. and Kirstein, A. F., Static Tests of Model L-809 (Modified)

Airport Marker Light Base and Mul t i -Electric Class BB Light, NHS Technical Report 7046 to Ship Aeronautics Division, Bureau of Naval Weapons,

December 1960.

2. In-Pavement Approach Light and Threshold Light Type 19975, Instruction

Book 7223 made in accordance with FAA Specification: FAA-E-2491, Sepco

Division, Connecticut International Corp.

3. Sushinsky, G. F., Static Tests of L-837 Airport Marker Light Bases,

NBS Technical Report 10453 to Federal Aviation Administration, July

1971.

4. Department of Transportation, Federal Aviation Administration Specification FAA-E-2491a, February 19, 1974.

9
APPENDIX A

TesL Program for the FAA-E-2491 Lights

A. Old style lights from Newark Airport.

1. The light with the pushed in prism will be used for study or practice only.

2. The light without obvious damage shall be tested with the con- centrated load. The light with attached base unit shall be mounted

on one of the encased bases and outer rings. All screws shall

be tightened to the torque indicated in SEPCO's Instruction Book

7223. The load shall be applied to the center of the top of the

light through the 6-inch diameter, 1^-inch thick steel plate

without the rubber pad or other load block. The total load of

80,000 pounds shall be applied at the rate of 20,000 pounds per

minute and the full load maintained for 2 minutes. The light

shall have no evidence of cracking or breaking of top assembly

or of any component which could cause leaks or permanent distortion (:o cause shifting of light output.

B. New style lights purchased from SEPGO.

1. Preparations for tests.

a. Encase three type LB-4 bases in concrete suitable for

mounting the FAA-E-2491 lights including outer rings.

The concrete shall have a minimum thickness of 6-inches

around sides and bottoms of bases except for the hubs.

A conduit for bringing in power cables extending through

the concrete shall be attached to one of the hubs of each

base. Plywood covers, 22^-inches diameter by 1 3/8-inches

thick, shall be fastened to the bases with bolts and the

concrete around the covers shall extend out to the width

of the concrete encasing the bases but need not be a full

6-inches thick around the covers. The encasement may be

cast upside down but make certain the surfaces for the

outer rings are flat or slightly concave when in the upright positions. High early strength concrete should be

used to save time in completing these tests, but this

concrete should be cured for at least seven days before

load tests are started.

b. After removing the plywood covers, the threaded bolt holes

in the tops of the bases should be drilled out to 7/16-

inch diameter before installing the outer rings of the

1 i gh t s

.

c. Install the outer rings according to paragraphs 2.2 and

2.3 of SEPCO Instruction Book 7223 using suitable adhesive

and type P606 filler around the rings.

10
Static load tests.

a. Initial load test. Install an optical assembly with a complete sealed unit on one of the test bases and outer

rings. Without opening the sealed unit, connect the light

to a suitable power source. Before load tests begin, make

the initial photometric scans to obtain the data for reference on light output displacement. Then with the power

disconnected, make the distributed load tests. For this

test, the 1-inch thick rubber pad of Shore A hardness

of 55 to 65 is placed over the light, a flat steel plate

18 to 22 inches diameter and 3/4-inch thickness is centered

over the light (no contouring except for the rubber pad

is required.) The load may be applied directly to this

steel plate or through a 6-inch diameter 1^-inch thick

steel plate. The distributed load for this test will total

76,000 pounds which will be applied at the rate of 20,000

pounds per minute, and the total load is held for 5 minutes.

After removing the load, inspect for breakage or damage.

If damage is not detected, make a concentrated load test.

This test is made by applying the load directly to the

top center plate without the rubber pad. The load is applied

at the rate of 20,000 pounds per minute to a total of

80,000 pounds which is held for 2 minutes. Remove the

load, inspect for breakage or damage, and make the photometric scans to check for permanent displacement of the

light output. If the light withstands this load satisfactorily, repeat the concentrated load test to a total

of 150,000 pounds and hold for 2 minutes, or load to failure. Remove the load, inspect for damage, and make the

photometric scans for light output displacement,

b. Strain gage load test. If the light withstood the previous

testing use the same light, or if it failed, use another

light, remove the sealed unit and install strain gages

at points of interest for continued load testing. After

the strain gages are installed, mount the light top assembly on a test base and outer ring. Apply the concentrated

load test as above to light failure or to 250,000 pounds

whichever occurs first. Remove load and inspect for damage.

Impact tests.

a. Initial impact test. A complete light unit shall be installed on a test light base. A 5 pound steel ball case hardened

to Rockwell C50 to C53 shall be dropped from a height

of 6-fect on the center of the light unit. Examine the

light for breakage, cracking or deformation that could

cause leaks or shift the light output pattern.

II
J.

b. If the light withstands the initial impact test, continue

to make impact tests on other areas of the top assembly

to make impact tests on other areas of the top assembly

to determine the capability of the light to withstand

this impact.

USCOMM-NBS-D(

12
Figure 1 - SCHEMATIC OF AIRPORT MARKER LIGHT ASSEMBLY MOUNTED IN CONCRETE
Figure 2 - Type FAA-E-2491 Airport Marker Light Installed

in LB-4 Base Encased in Concrete Cylinder
GLASS PRISM

SECTION A-A

Figure 3 - SCHEMATIC OF OPTICAL COVER ASSEMBLY FOR FAA -E-2491 LIGHT SHOWING

STRAIN GAGE LOCATIONS IN RECESSED AREA BEHIND PRISM

AND ON PRISM SURFACE
Figure 4 - Static Test Setup Using 6-Inch Diameter Steel

Plate for Loading Top of Light Assembly

Figure 5 - Static Test Setup Using Rubber Pad

for Loading Top of Light Assembly
Figure 6 - Impact Test Setup in 400,000 ibf-Capacity Universal Testing Machine
Figure 7b - Closeup of Prism Fracture in New Style FAA-E-2491 Light
SERIAL NO. 6 79 ILOAD APPLIED THROUGH RUBBERPAD)

O SERIAL NO. 676(L0AD APPLIED THROUGH STEEL PLATE)

250,000

200,000

150,000

100,000

50,000 -

.200 .300

DEFLECTION ,in

Figure 8 - LOAD VERSUS DEFLECTION OF OPTICAL COVER ASSEMBLY FOR NEW STYLE

FAA-E-2491 APPROACH AND THRESHOLD LIGHT
250 000

200,000

150,000

100,000

50,000

SERIAL NO. 676 ( LOAD

APPLIED THROUGH STEEL

PLATE 1 O

O

.O

O

O

O O

O O

' O

" O

' o o

o o

o o

o o

o o

o o

o o

o o

o o

00

o

SERIAL NO. 679 ( LOAD APPLIED

THROUGH RUBBER PAD I

2,000 4,000

STRAIN xlO

6,000

6

8,000 10,000

Figure 9 - LOAD VERSUS STRAIN AT GAGE LOCATION 3 ON OPTICAL COVER ASSEMBLY

FOR NEW STYLE FAA-E-2491 APPROACH AND THRESHOLD LIGHT
250,000

200,000

SERIAL NO. 676

[LOAD APPLIED THROUGH

STEEL PLATE)

150,000

100,000

X GAGE 4 + GAGE 5

50,000

t X

+ X

+ X

+ X

t X

t X

+ X

+ X

+ X

-I- X ) + X

-f- x>|-

+ Xj- ++ +x

+XX

x+

^ H- X +

X +

x +

x+

x-l- ^\_ SERIAL NO. 6 79-

XI- ILOAD APPLIED THROUGH

RUBBER PAD!

-3,000 -2,000 -1,000 0

STRAIN xio'

1,000 2,000 3 000

FigurelO - LOAD VERSUS STRAIN AT GAGE LOCATION 4 AND 5 ON OPTICAL COVER

ASSEMBLY FOR NEW STYLE FAA-E-2491 APPROACH AND THRESHOLD LIGHT
SERIAL N0.676(L0AD APPLIED

THROUGH STEEL PLATE) < a <

<

< < <

< <

< <

U < <

V

°< °< V SERIAL NO. 67 9 (LOAD APPLIED

< < THROUGH RUBBER PAD)

< < CW <1 3 < 3 D <

131 < am

a [33

< VERTICAL GAGE (COMPRESSION)

D HORIZONTAL GAGE (TENSION)

100 200

STRAIN X 10

300

-6

400 500

Figure ll - LOAD VERSUS STRAIN AT CENTER OF PRISM FOR NEW STYLE FAA-E-2491

APPROACH AND THRESHOLD LIGHT
Figure 12 - Fracture of Optical Cover Assembly of Old Style FAA-E-2491

Light After Static Test Using 6-Inch Diameter Steel Plate

co

•H

4J

CO AJoug

•I-I OJ

0)

a <u o u MD

.—4 c f—1

•H CO •H

CO CO 3 U-i (U IJ-J 1—4 u

•H 3 u-l QJ QJ (1) QJ CO o iJ O l-i l-i V4 )-4 o D 3 3

OJ CO <u 4J 4-1 4-1 4J u 1-1 u o o o a c c CO CO <0 to

<y >-l >-i >^4

u

xl 00 u-l u-l U-4 u-l c -1 > > e e e e

4-1 QJ (0 (fl cn

0) •H •H •t-i •r4 o (0 o >-l )-l )-i >-l z u 2 a, Oi a, tu P bf o o O o o o o 3 ,—1 o o o o o o o e o m o m m o o

T5 o \0 <J- rsi <) CM

CO CO 00 1—1 m vO t—1 o m CM CM t—1

CM

1-3

<u Q> 0)

<J- 4J 4-1 4-1 <N CO to CO 1 t—1

—4 r-4

CxJ Oi Oi CU 1 CD OJ Q) QJ 4J r—1

4J iJ •—1 —1

(0 CO Q) CO CO Q> QJ I—1

>—t<U •—1 —1

4) QJ

<D cu Oi iJ Oi Pu 4-1 4-1 U CO CO CO o D .—t

1—4 r—l 4J a» (U a; <u QJ QJ 0) (A 4J X QJ OJ 00 0) 0) 00 00

•1-t

u 4J AJ >-l I-I Ul 00 [14 m (0 CO CO to to M J H J u >-l V4 V4 C <u 0) -o QJ T3

•1-1 •u 4-1 c c c

to ^ •o cu QJ <0 QJ to to o o CO ^

hJ Xi o p3 •o c9 T)

•r-l •r^ CO •1-1 to to

O 0)Q

Q

QQ a. &4

•H

u

u ja x: x: )-l x: x: )-l CO H u o QJ o o QJ QJ c c X) c c X) X3

(/) T5

M h-l XI

M I-I XI X) c 1 1 D 1 1 3 ^ CO 02 vO OS o

x;o U (0 .—I u

CO

O CO d)

g x> vO CO c>

vO 3 Oh CN vO vO vO

CO < 1

CO 2

•—1

QJ cu

r—l •—1 T3 "O jQ > •—1 ,—1 Q) <i> QJ Q) 1—1

(0 4-1 o O z z Z Z o H w
NBS-1UA (REV. 7-73)

1 U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

1 SHEET

1. PUHLIC ATION OR REPORT NO.

NBSIR 75-647

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

MFCHANTCAL TESTS OF FAA-E-2491 AIRPORT IN-PAVEMENT

APPROACH AND THRESHOLD LIGHTS

5. Publication Date January 1975

6. Performing Organization Code

7. AUTHOR(S)

Donald C. Robinson

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 2211500

11. Contract /Grant No.

12. Sponsoring Organization Name and ( omplete Address (Street, City, State, ZIP)

Federal Aviation Administration

Washington, D. C. 20234

13. Type of Report & Period Covered

Final

FAA

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factuat aummary of moat aigpHicant mtormatian. If document includes a significant

bibliography or literature survey, mention it here.)

Static and impact load tests were performed on two style FAA-E-2491 airport

in-pavement approach and threshold lights which were mounted in light bases encased

in concrete. Static tests were conducted using either a 6-inch diameter steel plate

or a rubber pad through which loads were applied to the center of the light optical

cover assembly. Drop tests were conducted using a 5-lb steel ball which was directed to impact at various locations on the optical cover assembly. The old

style lights were found to comply with load requirements for the current specification. The maximum load sustained by both style lights when loaded through a rubber

pad was about two-thirds of the maximum load sustained when loading directly through

the steel plate. A discussion is given of the photometric measurements of the light

beam displacement measured during the load tests, the deflections and strains of two new style lights measured under two loading conditions and the test procedures for

determining the performance of approach and threshold lights.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons

)

Airport approach and threshold lightsj glass prism; impact testsj light basest

optical cover assembly^ photometric measurements; static tests.

18. AVAILABILITY Unlimited

For Official Distribution. Do Not Release to NTIS

1 1 Order From Sup. of Doc, U.S. Government Printing Office Washineton. D.C. 20402. SD Cat. No. C13

03 Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

21. NO. OF PAGES

31

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

22. Price

USCOMM.DC 29042-P74