k= — 10.2 cm (4.0in.) —13 %

"Same as above"

FIGURE 2. Propeller with yellow tip paint scheme (stippled
area) taken from U.S. Air Force, T.0. 1-1-4.





% 9 — (U9"1)

we — (Ul 80)

wo Ib

wo 1'Z

% bo — (UIT) wo 2°2 =

% Gi— (UI)
% 21— (ulee)

% Gi— CULT

hv
a)

= cure
— (ug

v
!
|

)

wo €°Ol
w> ¢°O| —

wo ¢°Oo| —
ws ¢°O| —
wo ¢°0| —
wo. ¢o| —
w> ¢°O| —
ws ¢°O| —

wo 2°z —
wo [py —

,2A40QD SD auiDS,

Curo’9)
% Z1— (ules)
(ur org)
CuLorg)

% 22— (‘Ul O'9)

ws 2S] —
wo "ge —
wo acl —_—
wo 2°Sg| —

w2 2°s| —

(Left) U.S.
Navy scheme taken from MIL-M-25047-C (ASG) with

stippled area in red.

(Right) U.S. Army scheme

Two helicopter rotor paint schemes.

FIGURE 4.

with black and white asymmetrical stripes taken

from TB-746-93-2.



— 7.6 cm (3.0in.) —10%

—I15.2 cm (6.0in.) —19%
— 7.6 cm (3.0 in.)

"Same as above"

FIGURE 3. Propeller with red (stippled area) and white paint
scheme taken from U.S. Navy MIL-M-25047-C (ASG).


FIGURE 5. Three Piper Cherokee, Model 140, airplanes
positioned in the viewing area with an elevated
viewing platform.



Technical Report Documentation Page

T. Report No. 2. Government Accession No. 3. Recipient's Catalog No.
FAA-AM-78-29
4. Title and Subjitle 3. Report Dete

August 1978
CONSPICULTY ASSESSMENT OF SELECTED PROPELLER AND &. Performing Organization Code

TAIL ROTOR PAINT SCHEMES

[8. Performing Organization Report No.

- Avihor’s) “Kenneth W. Welsh, John A, Vaughan, and

Paul G. Rasmussen

. Performing Organization Name and Address 10. Work Unit No. (TRAIS)

FAA Civil Aeromedical Institute
P. 0. Box 25082 11. Contract or Grant No.
Oklahoma City, Oklahoma 73125

13. Type of Report and Period Covered

12. Sponsoring Agency Name ond Address
Office of Aviation Medicine
Federal Aviation Administration
800 Independence Avenue, S.W. 14. Sponsoring Agency Code
Washington, D.C. 20591 FAA

15. Supplementary Notes
Work was performed under Task AM-A-78-PHY-114,

16. Abstract
An investigation was conducted to rank the conspicuity of three paint schemes for
airplane propellers and two schemes for tail rotor blades previously recommended
by the U.S, military and British Civil Aviation Authority, Thirty volunteer sub~
jects with normal vision viewed rotating propellers at 6.1 m (20 ft) and tail
rotor blades at 9.1 m (30 ft) under bright sunlight conditions. Observations of
the grouped airplanes and helicopters were made from three angles that included
(i) viewing upward from a crouched position, (ii) at eye level while standing,
and (iii) downward from an elevated platform.
At all viewing angles, the propeller design consisting of black and white stripes
asymmetrically placed on opposing blades was judged "most conspicuous" by ‘a wide
margin. The red and white stripe design (symmetrically placed) was considered
slightly more effective than the yellow tip design.
O£ two designs for tail rotors, the black and white asymmetrical stripe scheme was
chosen "more conspicuous" (9 to 1 ratio) than a red, white, and black stripe
design.

17. Key Words 18, Distribution Statement
Conspicuity Enhancement Document is available to the public through
Aircraft Propellers : . ° .

. the National Technical Information Service,

Paint Schemes Springfield, Virginia 22161
Ground Safety pring » Virg .

19. Security Classif, (of this report) 0, Security Classif. (of this page) 2. No. of Pages | 22. Price
Unclassified Unclassified 23

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized







Ill.

(info. Circular 104/1973) approximate those used by the

U.S. Army. Stripe width dimensions are specified in fixed
values for all sizes of propeller/rotor blades in U.S. Navy
and Air Force documents. U.S. Army specifications require
painting of the entire blade and therefore give stripe widths
in percentage values. The Federal Standard Color numbers for
the acrylic lacquer paints used in the evaluation were 17875,
37038, 31136, and 33538 for colors white, black, red, and
yellow, respectively.

Three Piper Cherokee airplanes (Model 140) were positioned
wing-to-wing in a semicircular fashion facing a central viewing
area. Two Bell helicopters (Series B47G, open tail) were
positioned nose-to-tail at a distance of approximately 90 m
(300 ft) from the airplanes. The viewing areas, sectioned off
by pylon-type markers, were located 6.1 m (20 ft) from the
airplanes and 9.1 m (30 ft) from the helicopters. A photograph
of the airplane viewing area is shown in Figure 5.

Thirty naive volunteer FAA employees with normal distant
visual acuity and color vision were transported in groups of
five to the viewing areas. Subjects viewed the propellers
and rotors from three positions that included: (i) looking
upward from a crouched position, (ii) while standing, and (iii)
viewing downward from a maintenance stand. The background for
each aircraft varied somewhat and consisted of shadows cast by
the aircraft, the surrounding landscape including hangars, and
other aircraft on the ramp. Observations were made looking
generally northward between 1300 and 1530 (CST) on November 17,
1977, under clear sky conditions. During the observation
periods, contract pilots maintained propeller and rotor speeds
at 1,000 and 2,300 rpm, respectively. Motion picture sequences
and still photographs were taken while propeller/rotor blades
were stationary and while rotating (Figures 6-15). Viewing areas
for the helicopters can be inferred from Figures 12-15.

Results.

The distribution of the relative conspicuity rankings of
the three propeller paint schemes is shown in Table 1, and the
frequencies with which each scheme was ranked "most conspicuous"
at each viewing angle are expressed as percentage values in
Figure 16.

The black and white asymmetrically striped scheme was
judged "most conspicuous" more frequently at all three viewing

6


— 47 cm (1.8in.) —6%
— 3.15 cm (1.2in.) —4%
—lIl.8 cm (4.6in.) —15 %

— 11.8 cm

— 11.8 cm
— 11.8 cm

— |1.8 cm

— 11.8 cm

— 11.8 cm

— 11.8 cm
—!1.8 cm

— 11.8 cm
— 11.8 cm

—15.0 cm (5.9in.) —1I19 %
— 4.7 cm (1.8 in.)

FIGURE 1. Propeller with black and white paint scheme and
asymmetrical stripes taken from U.S. Army,
TB-746-93-2.




II.

CONSPICULTY ASSESSMENT OF SELECTED
PROPELLER AND TAIL ROTOR PAINT SCHEMES

Introduction.

The U.S. National Transportation Safety Board (NTSB) has
reported that accidents from propeller and tail rotor blades
have resulted in 82 fatalities and 158 serious injuries from
1965 to 1974 (3). Furthermore, NTSB data indicate that pro-
peller/rotor contact injuries have steadily increased from
17 in 1965 to 30 in 1974. Causative factors associated with
helicopter rotor accidents involving 17 fatalities are dis-
cussed in an article by Kiel (2).

Federal Aviation Regulations (FAR) Parts 27 and 29 (par.
1565) for Normal Category Rotorcraft and Transport Category
Rotorcraft, respectively, state that, "Each tail rotor must
be marked so that its disc is conspicuous under normal daylight
ground conditions." However, FAR Parts 23 and 25 (par. 905)
for Normal, Utility, and Acrobatic Category Airplanes and
Transport Category Airplanes, respectively, do not specify
requirements to enhance conspicuity of airplane propellers.
In addition, no conspicuity requirements were found in FAR
Part 35 pertaining to airworthiness standards for aircraft
propellers.

In 1975, the FAA initiated a study designed to evaluate
the effectiveness of several paint schemes. However, the
investigations were halted prematurely when the DC-3 test
aircraft was damaged during takeoff in March 1975. The present
requested study was conducted to rank the visual effective-
ness (see and avoid) of three paint schemes for airplane pro-
pellers and two schemes for helicopter tail rotor blades cur-
rently used by the U.S. military services.

Methods.

Paint scheme specifications for each of three airplane
propellers (Figures 1-3) were taken from: (i) U.S. Army,
TB-746-93-2, (ii) U.S. Air Force, T.O. 1-1-4, and (iii) U.S.
Navy, MIL-M-25047-C, (ASG). Specifications for two helicopter
tail rotor blades (Figure 4) include U.S. Navy, MIL-M-25047-c,
(ASG) and U.S. Army, TB-746-93-2. Propeller/tail rotor speci-
fications recommended by the British Civil Aviation Authority

1