Document ID: FAA-2012-0045-0001
Agency: faa
Document Type: Proposed Rule
Title: Exclusion of Tethered Launches From Licensing Requirements
Posted Date: 2012-08-23T04:00Z

[Federal Register Volume 77, Number 164 (Thursday, August 23, 2012)]
[Proposed Rules]
[Pages 50956-50963]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-20686]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 400 and 401

[Docket No.: FAA-2012-0045; Notice No. 12-05]
RIN 2120-AJ90

Exclusion of Tethered Launches From Licensing Requirements

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to exclude tethered launches as defined in 
this proposal from the existing licensing requirements. This proposed 
rule would maintain public safety for these launches by providing 
launch vehicle operators with clear and simple criteria for a safe 
tethered launch. The FAA would not require a license, permit or waiver 
for tethered launches that satisfy the design and operational criteria 
proposed here.

DATES: Send comments on or before October 22, 2012.

ADDRESSES: Send comments identified by docket number FAA-2012-0045, 
using any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the online instructions for sending your 
comments electronically.
     Mail: Send comments to Docket Operations, M-30; U.S. 
Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room 
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
     Hand Delivery or Courier: Take comments to Docket 
Operations in Room W12-140 of the West Building Ground Floor at 1200 
New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
     Fax: Fax comments to Docket Operations at (202) 493-2251.
    Privacy: The FAA will post all comments it receives, without 
change, to http://www.regulations.gov, including any personal 
information the commenter provides. Using the search function of the 
docket Web site, anyone can find and read the electronic form of all 
comments received into any FAA dockets, including the name of the 
individual sending the comment (or signing the comment for an 
association, business, labor union, etc.). DOT's complete Privacy Act 
Statement can be found in the Federal Register published on April 11, 
2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov.
    Docket: Background documents or comments received may be read at 
http://www.regulations.gov at any time. Follow the online instructions 
for accessing the docket or Docket Operations in Room W12-140 of the 
West Building Ground Floor at 1200 New Jersey Avenue SE., Washington, 
DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays.

FOR FURTHER INFORMATION CONTACT: For technical questions concerning 
this proposed rule, contact Shirley McBride, Commercial Space 
Transportation, Federal Aviation Administration, 800 Independence 
Avenue SW., Washington, DC 20591; telephone (202) 267-7470; email 
Shirley.McBride@faa.gov.
    For legal questions concerning this proposed rule, contact Sabrina 
Jawed, AGC-240, Office of the Chief Counsel, Federal Aviation 
Administration, 800 Independence Avenue SW., Washington, DC 20591; 
telephone (202) 267-8839; email Sabrina.Jawed@faa.gov.

SUPPLEMENTARY INFORMATION: See the ``Additional Information'' section 
for information on how to comment on this proposal and how the FAA will 
handle comments received. The ``Additional Information'' section also 
contains related information about the docket, privacy, and the 
handling of proprietary or confidential business information. In 
addition, there is information on obtaining copies of related 
rulemaking documents.

[[Page 50957]]

Authority for This Rulemaking

    The Commercial Space Launch Act of 1984, as amended and re-codified 
at 51 U.S.C. 50901-50923 (the Act), authorizes the Department of 
Transportation and thus the FAA, through delegations, to oversee, 
license, and regulate commercial launch and reentry activities, and the 
operation of launch and reentry sites as carried out by U.S. citizens 
or within the United States. 51 U.S.C. 50904, 50905. The Act directs 
the FAA to exercise this responsibility consistent with public health 
and safety, safety of property, and the national security and foreign 
policy interests of the United States. 51 U.S.C. 50905. Title 51 U.S.C. 
50901(a)(7) directs the FAA to regulate only to the extent necessary, 
in relevant part, to protect the public health and safety and safety of 
property. The FAA is also responsible for encouraging, facilitating, 
and promoting commercial space launches by the private sector. 51 
U.S.C. 50903.

I. Background

    The FAA's licensing and permitting requirements for commercial 
space launches are contained in 14 CFR chapter III. Section 400.2 
specifies the requirements in chapter III apply to commercial space 
transportation activities conducted in the United States or by a U.S. 
citizen, but do not apply to amateur rocket activities or to space 
activities carried out by the United States Government on behalf of the 
United States Government.
    The FAA began hearing of tethered launches around 2002, when launch 
operators tested relatively small vehicles tethered to the ground with 
engines that burned for short periods of time. Operators later tested 
larger, more developed and costly vehicles by attaching them to a 
tether and attaching the tether to a crane or forklift to prevent the 
vehicle from hitting the ground. Some of these tethered launches met 
the FAA's amateur rocket activity criteria,\1\ and thus were excluded 
from chapter III requirements. Those that did not meet the amateur 
rocket criteria should have been required to comply with chapter III. 
However, because these launches had a tether system that restrained the 
vehicle within a certain range, the FAA initially deemed them low risk 
and did not require operators to conduct tethered launches under 
chapter III. In 2008, the FAA reassessed this determination and found 
that launches that meet the applicability criteria of Sec.  400.2, 
regardless of whether the launch vehicle is restrained by a tether, 
must be conducted under chapter III. That is, operators must apply for 
a license, permit or waiver. That year, the FAA reviewed and granted 
five chapter III waiver requests to conduct tethered launches. The 
agency now seeks an approach to tethered launches that would maintain 
public safety and be less burdensome on launch operators and the FAA. 
That approach is the subject of this proposed rule.
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    \1\ Prior to 2008, ``amateur rocket activities'' was defined in 
14 CFR Sec.  401.5 as ``launch activities conducted at private sites 
involving rockets powered by a motor or motors having a total 
impulse of 200,000 pound-seconds or less and a total burning or 
operating time of less than 15 seconds, and a rocket having a 
ballistic coefficient--i.e., gross weight in pounds divided by 
frontal area of rocket vehicle--less than 12 pounds per square 
inch.'' In 2008, the FAA moved the definition to 14 CFR part 1, 
chapter I and revised it as follows: ``Amateur Rocket means an 
unmanned rocket that is propelled by a motor or motors having a 
combined total impulse of 889,600 Newton-seconds (200,000 pound-
seconds) or less; and cannot reach an altitude greater than 150 
kilometers (93.2 statute miles) above the earth's surface.'' 14 CFR 
1.1; Requirements for Amateur Rocket Activities, Final Rule, 73 FR 
73781 (Dec. 4, 2008).
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II. Overview of Proposed Rule

    Title 51 U.S.C. 50901(a)(7) directs the FAA to regulate only to the 
extent necessary, in relevant part, to protect the public health and 
safety and safety of property. Therefore, the FAA proposes to reduce 
the scope of chapter III by excluding tethered launches that meet the 
requirements of this proposed rule. This proposal would maintain public 
safety by creating threshold criteria to determine whether chapter III 
needs to apply. FAA oversight would no longer be required for these 
launches because of the comprehensive protection the proposed launch 
vehicle, tether system, and operational criteria would provide.
    This rulemaking would not affect amateur rocket activities, 
regardless of whether they include a tether system, because chapter III 
regulations do not apply to the launch of amateur rockets. Those 
operators that conduct launches covered under chapter III and are not 
eligible for the exclusion proposed here, must continue to follow 
current requirements by applying for a license, permit or waiver.
    The FAA is proposing a number of changes consistent with the goals 
of Executive Order 13610, Identifying and Reducing Regulatory Burdens, 
77 FR 28469 (May 14, 2012). This proposal, if adopted, would require 
that the launch vehicle be unmanned, be powered by a liquid or hybrid 
engine, and carry no more than 5,000 pounds of propellant. It would 
also require that the tether system, including the points of attachment 
within the tether system, meet specified structural criteria, and that 
the tethered operations be carried out within specified separation 
distances from the public. The structural criteria would mitigate the 
hazards that can compromise the structural integrity of the tether 
system. The vehicle requirements and operational criteria would provide 
additional protection to the public by mitigating potential hazards 
posed by a tether system failure.
    The proposed rule would alleviate burdens on both the vehicle 
operator and the FAA. The operator would no longer incur the costs 
associated with submitting a launch license application, permit 
application or petition for waiver under chapter III. In addition, the 
operator would not incur the costs associated with any delay in 
processing applications or waivers. Finally, the FAA would not have to 
evaluate applications, conduct independent analyses, or issue licenses, 
permits or waivers.

III. Discussion of the Proposal

    This proposal would amend two sections of part 400. It would revise 
Sec.  401.5 (Definitions) to add a definition for a tether system. It 
would also revise Sec.  400.2 (Scope) to add requirements for the 
launch vehicle and tether system, as well as separation distances from 
the public for the tethered launch operations.

A. Proposed Definition (Sec.  401.5)

    The FAA proposes to define tether system as a device that would 
contain launch vehicle hazards by physically constraining a launch 
vehicle in flight to a specified range from its launch point. A tether 
system includes all components, from the point of attachment to the 
vehicle to a solid base, that experience load during a tethered launch.
    A tether system should prevent a vehicle from departing the launch 
site because the vehicle could pose a hazard to the public. Typically, 
a tether system is composed of at least three parts: one vehicle 
connection; one fixed connection; and at least one tether that has one 
end fastened to the vehicle connection and the other end fastened to a 
fixed connection to a solid base so as to limit the vehicle's range of 
movement. A vehicle connection consists of all mechanical components 
that attach a tether to a launch vehicle. These include, for example, 
metal frames, bolts that attach the vehicle and metal frame together, 
and shackles. A fixed connection attaches a tether to a solid base, 
such as a crane, a forklift or

[[Page 50958]]

the ground, and it consists of all mechanical components that 
accomplish the attachment. Examples of these mechanical components 
include the component that attaches any crane to the rest of the 
system, such as shackles or a bolt that attaches a solid base and 
shackle together.
    The FAA's proposed definition is broad enough to encompass all 
possible tether system configurations. This proposed definition would 
require operators, when determining if chapter III applies, to account 
for the effect of a tethered launch on every component from the point 
of attachment to the vehicle to a solid base, that experience load 
during a tethered launch. Accounting for a whole system would reduce 
the likelihood of a system failure caused by an overlooked component 
that was unable to withstand the maximum load exerted on it.
    In devising a tether system, the operator should take into account 
the vehicle's structural integrity because if the tether were able to 
withstand the forces exerted on it, but the vehicle could not, then the 
vehicle could break free. If this were to happen and the vehicle 
exceeded the proposed flight limit of 75 feet above ground level (AGL), 
the operator would have failed to comply with the proposed requirement 
in Sec.  400.2(c)(2)(iii).
    The FAA's proposed definition accounts for only one tether, 
regardless of any other tethers within the system. A tether system 
containing multiple tethers or multiple attachment points is not 
necessarily more reinforced or safer: all of the applied forces may not 
be evenly distributed among the tethers. For instance, for a tether 
system with four tethers, if an operator assumes that the maximum load 
is evenly distributed among all four tethers of the system and designs 
each tether to withstand one-fourth of the maximum load, the entire 
tether system could fail if the vehicle's position shifted and more 
than one-fourth of the maximum load was placed on a single tether. In 
other words, if one tether can fail, then all tethers within the system 
can fail. Accordingly, in order to reduce the likelihood of a tether 
system failure, the system must contain at least one tether capable of 
bearing the maximum force exerted on the tether system, regardless of 
the number of additional tethers within the system. Increasing the 
number of tethers within the system does not guarantee an increase in 
strength for the overall system.

B. Proposed Launch Vehicle (Sec.  400.2 (c)(1))

    In order to avoid the applicability of chapter III, the FAA 
proposes that a launch vehicle would have to be unmanned and meet the 
requirements proposed below.
1. Engine Type
    The FAA would require a launch vehicle excluded by tether from 
chapter III to have a liquid or hybrid motor; a solid rocket motor 
would not be permitted. Liquid or hybrid motors are composed of systems 
that require mixing of the propellants to combust, whereas solid motors 
consist of relatively simple systems where the propellants are already 
formulated with oxidizer dispersed in fuel. If a tethered vehicle were 
to lose control, the operator would rely on the tether system to 
constrain the vehicle and bring it to the ground. The fragile nature of 
liquid or hybrid motors ensures that ground impact would render them 
inoperable.
2. Propellant Cap
    The FAA would not permit a launch vehicle to carry more than 5,000 
pounds of propellant. The FAA's records indicate that, historically, 
the most propellant that has been on board a launch vehicle for a 
tethered launch is approximately 1,000 pounds. Greater propellant 
amounts result in both a heavier launch vehicle and greater explosive 
energy.
    To determine this proposed cap, the FAA assessed the weight 
capacity of cranes and forklifts from a random sampling and from data 
used during past tethered launches. The data from the past launches 
indicate that the average weight capacity of these crane or forklift 
tether systems was 6,000 pounds; however, there were gaps in the data 
because this information was voluntary and not all operators provided 
it. To fill in the gaps, the FAA randomly selected eleven crane and 
forklift models from several manufacturers.\2\ The data obtained from 
the random samples indicate that the average weight capacity of a crane 
or forklift is also approximately 6,000 pounds. For a tethered vehicle, 
the vehicle's dry weight uses a maximum of approximately 15 percent of 
the crane or forklift weight capacity.\3\ This leaves approximately 85 
percent of the weight capacity available for the propellant. To compute 
the maximum propellant amount that a tethered vehicle can carry, the 
FAA took the 6,000-pound crane or forklift weight capacity and 
multiplied it by 85 percent. This computation resulted in a maximum 
propellant weight of 5,100 pounds. To provide a margin for the weight 
capacity of the crane or forklift, the FAA rounded this value down to 
5,000 pounds.
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    \2\ Models from the random sampling consisted of the Broderson 
IC20, Broderson IC35, Case 586G, JCB 930, John Deere 486E, Genie 
GTH5519, Genie GTH636, Genie GTH644, Gradall G6-42Z, Gradall G6-42P, 
Lull 644E-42.
    \3\ Some operators provided voluntary information on their 
tether systems. The FAA looked at the different vehicles' dry 
weights relative to the crane or forklift weight capacity.
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C. Proposed Tether System (Sec.  400.2(c)(2))

    The FAA proposes conservative technical and design criteria for an 
effective tether system. The FAA developed these criteria by 
determining what would prevent a tether from breaking and exposing the 
public to launch vehicle hazards. The FAA proposes five criteria as 
necessary to reduce the risk of a tether system failure: (1) 
Established strength properties, (2) minimum factor of safety, (3) 
launch vehicle constraint, (4) no damage displayed before launch, and 
(5) protection from launch vehicle exhaust plume.
1. Established Strength Properties
    The FAA would require that an eligible tether system have 
established strength properties that would not yield or fail under the 
maximum dynamic load on the system or under a load equivalent to two 
times the maximum potential engine thrust.
    Because some operators may not readily know the maximum dynamic 
load for their tether systems, the FAA proposes an alternate means of 
determining whether the tether is of sufficient strength. If an 
operator does not know the maximum dynamic load, the operator may 
calculate the maximum load as follows: determine the maximum potential 
engine thrust of the tethered vehicle and then multiply the maximum 
engine thrust by a factor of two. Using the maximum potential engine 
thrust of two is an industry standard for estimating the dynamic load 
of any structural system.\4\
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    \4\ See A.E.H. Love, A Treatise on the Mathematical Theory of 
Elasticity, 179-180, Cambridge University Press (2d ed. 1906).
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2. Minimum Factor of Safety
    The FAA would require operators to multiply the maximum load by a 
minimum factor of safety \5\ of 3.0 for

[[Page 50959]]

yield stress and 5.0 for ultimate stress. All components would have to 
have established strength properties that could withstand the maximum 
load multiplied by the factors of safety. The FAA chose the proposed 
factors of safety based on their successful history in a similar 
context.
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    \5\ A factor of safety of 1.0 implies that the design meets 
minimum requirements, but is on the point of failure with design 
uncertainties and no margin for variation or error. A factor of 
safety less than 1.0 means the design does not meet the minimum 
requirements and is in a failed state. A factor of safety greater 
than 1.0 means the design exceeds the requirements by a multiple of 
that factor of safety and is in a safety state.
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    The U.S. Air Force has used these same factors for similar 
operations. The U.S. Air Force conducts rocket operations at the 
Eastern and Western Ranges, including of tethered and ground-based 
systems. It recommends a minimum factor of safety of 3.0 for yield 
stress,\6\ and a factor of safety of 5.0 for ultimate stress,\7\ for 
the design of ground-based systems. This includes the tether and its 
attachments to launch facilities or ground equipment.\8\ This means 
that for a tether system, the components within the system would be 
able to endure three times the force required to permanently deform the 
components, and five times the force required to break the components. 
The U.S. Air Force has not experienced any tether failures, even for a 
Minuteman launch, using these factors.
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    \6\ Yield stress is the elastic limit.
    \7\ Ultimate stress is when breakage occurs.
    \8\ Nicholas E. Martino, Design and Analysis Guidelines for 
Launch Vehicle Tether Systems, Aerospace Report No. ATR-2008 (5377)-
1, The Aerospace Corporation (Sept. 30, 2007). This report is 
available in the docket for this rulemaking (Docket No. FAA-2012-
0045).
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3. Launch Vehicle Constraint
    The FAA proposes that the launch vehicle be constrained so that its 
flight cannot exceed 75 feet AGL. This altitude limit is based on the 
FAA's assessment of historical data on tether lengths and on the height 
of cranes and forklifts to determine a safe maximum altitude for tether 
systems. Based on this assessment, the FAA calculated an average crane 
or forklift height and an average tether length. The FAA then added 
these two values together to determine the launch vehicle's potential 
altitude.
    Crane and forklift data from previous tethered launches and 
sampling indicate that the average height of the crane or forklift in a 
tether system is 43 feet. There were gaps in the data because the 
information was voluntary, and not all operators provided it. To fill 
the gaps, the FAA examined random samples of different crane and 
forklift heights, which indicated that operators typically use mid-
sized cranes and forklifts to conduct their tethered operations. The 
FAA then took samples of mid-sized cranes and forklifts and averaged 
their heights and weight capacities to determine their physical 
limitations. The FAA obtained the samples from online brochures of 
manufacturers of cranes and forklifts.\9\ The sample information also 
indicates that the average crane or forklift height is approximately 43 
feet.
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    \9\ These included Broderson Manufacturing Corp.; JCB; Genie; 
and Gradall Industries, Inc.
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    A launch vehicle's potential altitude is a crucial element in 
determining how far debris can travel in the event of a crash or an 
explosion. Large tether lengths allow for high altitude flights, while 
short tether lengths limit the vehicle to low altitudes. This means 
that a tether system failure during flight can result in large vehicle 
ranges for long tethers and short vehicle ranges for short tethers, 
because altitude and range are proportional. In order to reduce the 
risk to the public during tethered launches, the tether length must not 
be too long. An appropriate length is also necessary to prevent 
hazardous events, such as the entanglement of the tether with launch 
support structures or other facilities. Moreover, an appropriate tether 
length would prevent a controlled airspace incursion.
    The FAA assumed that the maximum tether length for the average 
crane or forklift tether system would not be greater than the crane or 
forklift height because such a tether length could allow a launch 
vehicle to hit the ground and possibly explode. The FAA also assumed 
that the tether must be given room to stretch, because a 43-foot tether 
attached to a 43-foot high crane could allow the launch vehicle to hit 
the ground when the length of the vehicle and the elasticity of the 
tether are taken into account. Based on these assumptions, the FAA 
concluded that the tether length should be less than 43 feet.
    The FAA examined past tether waiver applications to determine the 
appropriate tether length. The tether waiver data showed that the 
maximum tether length operators typically use is approximately 32 feet. 
The FAA would use a tether length of 32 feet, which provides a margin 
of 11 feet to account for the tether's elasticity and the length of the 
vehicle, to calculate maximum altitude. This length is appropriate and 
reasonable for tethered flights because past tethered flights have 
demonstrated that the length allows the vehicle sufficient lateral 
movement for operators to conduct tethered activities, while limiting 
the vehicle to low altitudes and thereby reducing the risk to the 
public.
    When the average crane or forklift height of 43 feet is added to an 
appropriate tether length of 32 feet, the result is a maximum potential 
altitude of approximately 75 feet for the tethered vehicle. 
Accordingly, the FAA proposes to require that the tether system 
physically constrain the launch vehicle within an altitude of 75 feet 
AGL. This altitude does not require operators to use 43-foot high 
cranes or 32-foot long tethers; those measurements were only used to 
calculate an appropriate maximum altitude for a tethered launch that 
would not require FAA oversight. The proposed maximum altitude would 
protect the public by limiting the launch vehicle's range.
4. No Damage Displayed Before Launch (Sec.  400.2(c)(3))
    The FAA would require that the tether system show no visual 
component damage before each launch. This requirement would reduce the 
risk of a tether system failure due to pre-existing damage. A visual 
check of the tether system before each launch could prevent failure by 
identifying signs of damage such as component fatigue, fracture, wear, 
creep, corrosion, yielding, or thermal shock. While the initial stages 
of some of these forms of damage may not be visible to the naked eye, 
they may eventually become visible. The FAA offers the following 
definitions of these terms as guidance in conducting the visual check:
    [ssquf] Fatigue is the progressive and localized structural damage 
that occurs when a material is subjected to cyclic loading. Fatigue 
occurs when a material is stressed repeatedly.
    [ssquf] Fracture is the local separation of an object or material 
into two or more pieces under the action of stress.
    [ssquf] Wear is the erosion of material from a solid surface by the 
action of another surface. Wear is related to surface interactions and 
more specifically to the removal of material from a surface as a result 
of mechanical action.
    [ssquf] Creep is the tendency of a solid material to move slowly or 
deform permanently under the influence of stresses.
    [ssquf] Corrosion is the disintegration of an engineered material 
into its constituent atoms due to chemical reactions with its 
surroundings.
    [ssquf] Yielding is when a material begins to deform plastically; 
when the yield point is passed, some fraction of the deformation will 
be permanent and non-reversible.
    [ssquf] Thermal shock is cracking as a result of rapid temperature 
change.

[[Page 50960]]

5. Protection From Launch Vehicle Exhaust Plume
    The FAA would require an operator to insulate or locate the tether 
system such that it will not experience thermal damage due to a launch 
vehicle's exhaust. This requirement would mitigate the risk of a tether 
system failure due to thermal damage. Components exposed to the heat 
emitted from a launch vehicle's exhaust plume may be damaged or 
severely weakened. Metallic components, for example, that are exposed 
to a vehicle's exhaust plume may not visually show damage; however, all 
structural materials suffer significant strength degradation at 
elevated temperatures.

D. Proposed Separation Distances (Sec.  400.2(c)(3))

    The FAA proposes that tethered launches be conducted at a 
sufficient distance from the public and from property belonging to 
members of the public to mitigate the effects when a launch vehicle 
unintentionally separates from the tether system. A launch vehicle may 
transfer unanticipated loads into the tether system, resulting in 
tether system failure and vehicle separation. Although a properly 
designed and constructed tether system should not fail, adding distance 
between the launch point and members of the public is a prudent and 
relatively simple and inexpensive safety measure to implement.
    The FAA computed its proposed separation distances by first 
calculating a conservative maximum range of a vehicle that broke free 
of the tether system, and then calculating the hazardous fragment 
distance from the point of impact based on the type and amount of 
propellants onboard. Table A--Separation Distances for Tethered 
Launches in proposed Sec.  400.2 would contain the separation distances 
required for a tethered launch that was excluded from chapter III. Each 
distance calculation in Table A is discussed below.
1. The Maximum Range of the Vehicle Released From the Tether
    To determine a launch vehicle's maximum range, the FAA used 
Newton's equations of motion to estimate the maximum possible distance 
a vehicle that broke free of a tether could travel. The FAA simulated 
the scenarios where a tether system failed, and the vehicle followed a 
ballistic trajectory to the ground. The analysis consisted of the 
following assumptions: (1) The vehicle would be non-propulsive upon 
release; (2) the initial release velocity of the vehicle was maximized; 
(3) the tether's pull would not reduce the vehicle's velocity; (4) the 
tether would fully extend upon release; (5) the release angle of the 
vehicle would be the angle that provided the maximum range; and (6) the 
vehicle would fly through a vacuum. Except for the non-propulsive 
nature of the vehicle, all assumptions are conservative from a public 
safety perspective. The non-propulsive assumption is reasonable because 
a vehicle that broke free of a tether would most likely be unstable and 
not able to sustain flight in any particular direction.
    The FAA also conducted a computer simulation of the same scenarios, 
using a trajectory analysis tool to verify the validity of the FAA's 
maximum range calculations. The numerical results from the computer 
simulation were consistent with the results from the FAA's 
computational analysis.
2. The Hazardous Fragment Distance Based on the Propellant Onboard
    Upon impact at its maximum range, a launch vehicle with liquid 
propellants has the potential to explode, creating both overpressure 
and debris hazards. Explosive hazards associated with propellant 
quantities up to 5,000 pounds are driven by fragment hazards. The FAA 
used the formulas provided in Table 1 below to determine the hazardous 
fragment distance given a launch vehicle impact. This distance is a 
function of the net explosive weight (NEW), or the explosive equivalent 
of the propellants used on the launch vehicle.\10\ Depending on the 
type of propellant, the explosive equivalent may vary from 10 to 20 
percent, in accordance with Table E-2 of part 420.\11\ For purposes of 
this rulemaking, the FAA applied a maximum NEW value of 20 percent for 
all propellant types. Using this conservative assumption simplifies the 
proposed rule.
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    \10\ The definitions of NEW and explosive equivalent weight are 
provided in 14 CFR 420.5.
    \11\ Explosive Siting Requirements, Notice of Proposed 
Rulemaking, 76 FR 8923 (Feb. 16, 2011).

                Table 1--Hazardous Fragment Distance \12\
------------------------------------------------------------------------
                                             Hazardous fragment distance
        Net Explosive Weight (NEW)                    (d), feet
------------------------------------------------------------------------
<=0.5 pounds..............................  d = 236
0.5 poundshttp://www.regulations.gov);
    2. Visiting the FAA's Regulations and Policies web page at http://www.faa.gov/regulations_policies or
    3. Accessing the Government Printing Office's web page at http://www.fdsys.gov. Copies may also be obtained by sending a request to the 
Federal Aviation Administration, Office of Rulemaking, ARM-1, 800 
Independence Avenue SW., Washington, DC 20591, or by calling (202) 267-
9680. Commenters must identify the docket or notice number of this 
rulemaking.
    All documents the FAA considered in developing this proposed rule, 
including economic analyses and technical reports, may be accessed from 
the Internet through the Federal eRulemaking Portal referenced in item 
(1) above.

List of Subjects

14 CFR Part 400

    Space transportation and exploration; licensing.

14 CFR Part 401

    Space transportation and exploration.

The Proposed Amendment

    In consideration of the foregoing, the Federal Aviation 
Administration proposes to amend Chapter III of Title 14 Code of 
Federal Regulations as follows:

PART 400--BASIS AND SCOPE

    1. The authority citation for part 400 continues to read as 
follows:

    Authority: 51 U.S.C. 50901-50923.
    2. Revise Sec.  400.2 to read as follows:

Sec.  400.2  Scope.

    These regulations set forth the procedures and requirements 
applicable to the authorization and supervision under 51 U.S.C. 
subtitle V, chapter 509, of commercial space transportation activities 
conducted in the United States or by a U.S. citizen. The regulations in 
this chapter do not apply to--
    (a) Space activities carried out by the United States Government on 
behalf of the United States government;

[[Page 50963]]

    (b) The launch of an amateur rocket as defined in Sec.  1.1 of 
chapter I; or
    (c) A launch that meets the following criteria:
    (1) Launch vehicle. The launch vehicle must--
    (i) Be unmanned;
    (ii) Be powered by a liquid or hybrid rocket motor; and
    (iii) Carry no more than 5,000 pounds of propellant.
    (2) Tether system. The tether system must--
    (i) Have established strength properties that will not yield or 
fail under--
    (A) The maximum dynamic load on the system; or
    (B) A load equivalent to two times the maximum potential engine 
thrust.
    (ii) Have a minimum safety factor of 3.0 for yield stress and 5.0 
for ultimate stress.
    (iii) Constrain the launch vehicle within 75 feet above ground 
level.
    (iv) Display no damage prior to the launch.
    (v) Be insulated or located such that it will not experience 
thermal damage due to the launch vehicle's exhaust.
    (3) Separation distances. The launch operator must separate its 
launch from the public and the property of the public by a distance no 
less than that provided for each quantity of propellant listed in Table 
A of this section.

           Table A--Separation Distances for Tethered Launches
------------------------------------------------------------------------
                                                           Distance (ft)
                Propellant carried (lbs)                     from the
                                                           launch point
------------------------------------------------------------------------
1-500...................................................             900
501-1,000...............................................           1,200
1,001-1,500.............................................           1,350
1,501-2,000.............................................           1,450
2,001-2,500.............................................           1,550
2,501-3,000.............................................           1,600
3,001-3,500.............................................           1,650
3,501-4,000.............................................           1,700
4,001-4,500.............................................           1,750
4,501-5,000.............................................           1,800
------------------------------------------------------------------------

PART 401--ORGANIZATION AND DEFINITIONS

    3. The authority citation for part 401 continues to read as 
follows:

    Authority: 51 U.S.C. 50101-50923.

    4. Amend Sec.  401.5 by adding the definition of tether system in 
alphabetical order to read as follows:

Sec.  401.5  Definitions.

* * * * *
    Tether system means a device that contains launch vehicle hazards 
by physically constraining a launch vehicle in flight to a specified 
range from its launch point. A tether system includes all components, 
from the point of attachment to the vehicle to a solid base, that 
experience load during a tethered launch.
* * * * *

    Issued in Washington, DC, on August 16, 2012.
George C. Nield,
Associate Administrator, Commercial Space Transportation.
[FR Doc. 2012-20686 Filed 8-22-12; 8:45 am]
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