Lunar Extravehicular Visor Assembly (LEVA)

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The bulk of this chapter deals with the LEVA as it was flown starting with Apollo 14. The following pictures show the simpler version flown on Apollo 11, 12, and 13, which included an inner protective visor, a sun visor, and side visors on the left and right. Details can be found in the sections describing the Apollo 14-17 LEVA.

 

Detail from 69-H-670 showing Neil Armstrong
during training with all his visors fully raised.
This picture gives us a good view of the tabs
with which the visors can be raised and lowered.

 

Detail from 69-HC-1037 showing Pete Conrad during training
with his protective visor about 1/3rd down
and his sun visor not lowered as far.

 

Detail from KSC-70PC-18 showing Fred Haise
with his protective visor fully down,
his gold-plated sun visor mostly down,
and his side visors about halfway down.
(Click on the image for a larger version.)

 

Detail from 70-HC-80 showing Fred Haise
with all his visors down.
This picture gives us a good view of the tabs.
(Click on the image for a larger version.)

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Apollo 14-17 LEVA

Detail from S70-46156 showing Alan Shepard
with the new LEVA introduced for Apollo 14.
The new version included a central sunshade with a raisable flap.
(Click on the image for a larger version.)

Section 2.3.5.9, Volume 1
Apollo Operations Handbook: Extravehicular Mobility Unit
Apollo 15-17
MSC-01372-1 / CSD-A-789-1

The LEVA is a light-and-heat attenuating assembly which fits over the clamps around the base of the Pressure Helmet Assembly (PHA). It provides additional protection from micrometeoroids and accidental damage to the PHA.

The LEVA consists of the following subassemblies.

a. Shell assembly
b. Shell cover assembly
c. Protective visor
d. Sun visor
e. Hub assemblies (2)
f. Latching mechanism
g. Side eyeshade assemblies (2)
h. Center eyeshade assembly

The shell assembly is a formed polycarbonate structure to which the visors, hinge assemblies, eyeshades, latch, and shell cover assembly are attached. The shell assembly latches around the pressure helmet at the neck ring, and, when the latch is secured, a rigid connection between the two assemblies is assured.

Adjacent to the visor hinge, straps constructed of polypropylene are employed across the cut-out support portions of the visor shell to permit flexual durability and to allow ease in spreading the visor during LEVA donning.

The shell cover assembly is constructed of seven layers of perforated, aluminized Mylar and six layers of nonwoven Dacron. The layers are arranged alternately to reduce interlayer heat transfer. The outer layer or covering is made of Teflon-coated Beta yarn for additional thermal and fire protection. Potential scuff areas on the forward edge are reinforced with Teflon fabric. Flameproof hook-and-pile fastener tape (Velcro) is used to attach the collar over the LEVA/ITMG or LEVA/CLA interface area.

The protective visor is an ultraviolet-stabilized polycarbonate shield which affords impact, micrometeoroid, and ultraviolet ray protection. It can be positioned anywhere between the full-Up and full-Down positions and requires a force of 2 to 4 pounds for movement. A coating is added to the inner surface of this assembly. The elastomer seal on the upper surface of the stiffener prevents light passage between the two visors. The protective visor can be lowered independently of the sun visor, but cannot be raised independently with the sun visor in the Down position.

The inner surface of the polysulfone sun visor has a gold coating which provides protection against light and reduces heat gain within the helmet. The visor can be positioned anywhere between the full-Up and full-Down positions by exerting a force of 2 to 4 pounds on the pull tabs. The sun visor cannot be independently lowered unless the protective visor is in the Down position, but it can be raised or lowered independently when the center eyeshade is in the full-Up position and the protective visor is in the Down position.

The hinge assemblies located on each side of the LEVA shell are support-and-pivot devices for the two visors and eyeshades. The hinge positions adjust for a proper fit of the visors to the shell and helmet assemblies and to aid in achieving a good light seal. Each hinge assembly is comprised of a bolt extending through a two-plece hub arrangement which supports dissimilar-material washers, the spacers, and a spring. Tension on the spring is adjustable and determines the force necessary for visor and side eyeshade movements. After adjustment, the hinge bolt is safe-tied with lock wire.

The latching mechanism is constructed of stainless steel and is used to secure the base of the LEVA shell around the PHA above the helmet neck ring. The over-center feature of the latch pulls the two sides of the front portion of the LEVA shell structure together and tightens it around the PHA. A lanyard attached to the actuating tab of the latch and the shell cover assembly permits easy actuation of the latch with a gloved hand The lanyard is visible when the collar is held open.

The eyeshade assemblies are constructed of fiberglass and are coated with white epoxy paint on the outer surfaces. The inner surfaces are coated with black epoxy paint. The side eyeshades are attached to the hinge assemblies and can be lowered independently of the sun visor and each other to prevent light penetration of the side viewing areas, thereby reducing low-angle solar glare.

The center eyeshade is attached to the LEVA shell assembly over the shell thermal cover and can be lowered independently of the side eyeshade assemblies. When sufficiently lowered, the viewport door may be positioned as required to reduce solar glare. The viewport door is held in the desired position by a ratchet mechanism integral with the hinge assembly. The center eyeshade assembly cannot be independently lowered unless the protective visor and the sun visor are in the down positions.