Guide to Commercial 

Reusable Launch Vehicle Operations and 

Maintenance 

Federal Aviation Administration 

Office of Commercial Space Transportation 

800 Independence Avenue, Room 331 

Washington, DC 20591 

Version 1.0 March 2005 iii 

Guide to Commercial Reusable Launch 

Vehicle Operations and Maintenance 

Version 1.0 

March 2005 

Federal Aviation Administration 

Office of Commercial Space Transportation 

800 Independence Avenue, Room 331 

Washington, DC 20591 
NOTICE 

Use of trade names or names of manufacturers in this document does not constitute an official 

endorsement of such products or manufacturers, either expressed or implied, by the Federal 

Aviation Administration. 
 

TABLE OF CONTENTS 

1. Introduction............................................................................................................. 1 

2. Purpose..................................................................................................................... 1 

3. Scope ........................................................................................................................ 2 

4. Applicability ........................................................................................................... 2 

5. Definitions............................................................................................................... 2 

6. RLV Maintenance ................................................................................................. 3 

7. RLV Support Personnel....................................................................................... 6 

8. RLV Operations..................................................................................................... 8 

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1. Introduction 

With the enactment of the Commercial Space Launch Act of 1998, the Department of 

Transportation, Federal Aviation Administration, (DOT/FAA) was given statutory 

authority to regulate reentry and reusable launch vehicle (RLV) activities. The 

DOT/FAA recognized that RLVs would require operations and maintenance safety 

criteria and standards to ensure that public safety was maintained at an acceptable level. 

Unlike expendable launch vehicles (ELVs), which are only flown once, RLVs are 

intended to be flown repeatedly by the RLV operator. The DOT/FAA must ensure that 

the RLV operator has procedures and processes that return an RLV to a safe condition for 

reflight. In 1999 the FAA, Associate Administrator for Commercial Space 

Transportation (AST), developed a White Paper on Commercial RLV Operations and 

Maintenance Considerations and submitted it to the Commercial Space Transportation 

Advisory Committee (COMSTAC) RLV Working Group for comments. In addition, the 

FAA/AST has used an outside contractor, RTI International, to help inform the process of 

developing RLV Operations and Maintenance guidance. The DOT/FAA developed and 

published a Final Rule on Commercial Space Transportation Reusable Launch Vehicle 

and Reentry Licensing Regulations on September 19, 2000, with an effective date of 

November 20, 2000. This Final Rule addressed operational flight restrictions, but it did 

not provide regulations for maintenance of an RLV. The preamble to this Final Rule 

stated that several commentators pointed out the need to begin addressing, through 

regulations the need for operations and maintenance standards that will facilitate reflight 

approval. In May 2003, the FAA/AST published Draft Guidelines for Commercial 

Reusable Launch Vehicle Operations and Maintenance and asked the COMSTAC RLV 

Working Group for comments. Taking into consideration these comments, the FAA/AST 

revised the Draft Guidelines and published Preliminary Guidelines for Commercial 

Reusable Launch Vehicle Operations and Maintenance in July 2004. The FAA/AST 

asked the COMSTAC RLV Working Group for comments and received consensus 

comments to the Preliminary Guidelines. These consensus comments were very helpful 

in compiling this guide. 

2. Purpose 

This guide was developed to provide industry with insight into what the DOT/FAA views 

as important considerations for operations and maintenance of RLVs. It also addresses 

what the FAA/AST may expect to review and evaluate in an application for a license or 

permit1

 concerning RLV operations and maintenance. 

1 Under the Commercial Space Launch Amendments Act (CSLAA) of 2004, a person may apply for an 

experimental permit for reusable suborbital rockets only for purposes of research and development to test 

new design concepts, equipment, or operating techniques; showing compliance with regulatory 

requirements; and crew training prior to obtaining a license. The DOT/FAA must decide whether to issue a 

permit within 120 days after receipt of a permit application, compared to 180 days, which is the time the 

DOT/FAA has to make a licensing determination. 

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3. Scope 

This guide addresses RLV operations and maintenance for both suborbital and orbital 

RLVs, including flights with and without humans onboard. Although developers may 

find the information in this document helpful, many years of RLV flight experience are 

required before an appropriate set of regulations for RLV operations and maintenance can 

be developed. 

4. Applicability 

The information in this guide applies to any RLV operator licensed or permitted under 49 

U.S.C. Chapter 701. FAA/AST recognizes the commercial RLV industry is in its infancy 

and believes that the guidance in this document represents reasonable and appropriate 

practices that will ensure public safety. 

5. Definitions 

Crew Any employee of a licensee or transferee, or of a contractor 

or subcontractor of a licensee or transferee, who performs 

activities in the course of that employment directly relating 

to the launch, reentry, or other operation of or in a launch 

vehicle or reentry vehicle that carries human beings. 

[49 U.S.C. § 70102(2)] 

Flight crew Any employee of a licensee or transferee, or of a contractor 

or subcontractor of a licensee or transferee, who is onboard 

a launch or reentry vehicle and performs activities in the 

course of that employment directly relating to the launch, 

reentry, or other operation of the launch vehicle or reentry 

vehicle.2 

Space flight participant An individual, who is not crew, carried within a launch 

vehicle or reentry vehicle. [49 U.S.C. §70102(17)] 

Suborbital rocket A vehicle, rocket-propelled in whole or in part, intended for 

flight on a suborbital trajectory, and the thrust of which is 

greater than its lift for the majority of the rocket-powered 

portion of its ascent. [49 U.S.C. §70102(19)] 

Suborbital trajectory The intentional flight path of a launch vehicle, reentry 

vehicle, or any portion thereof, whose vacuum 

2 Because the CSLAA does not distinguish between ground crew and crew onboard a vehicle, the 

FAA/AST guidelines use the term “flight crew” to identify the crew onboard a vehicle. 

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instantaneous impact point does not leave the surface of the 

Earth. [49 U.S.C. §70102(20)] 

6. RLV Maintenance 

6.1. The applicant should have a maintenance program plan to facilitate 

maintenance and repair actions in the anticipated RLV operation environments. 

The maintenance program plan should be systematically formulated in the early 

conceptual design phase of the program to minimize problems during the 

operational phase. 

Rationale: Having a maintenance program plan can help to assure continuous 

flightworthiness of RLVs. The maintenance program plan should include scheduled and 

unscheduled maintenance. Scheduled maintenance is intended to maintain the vehicle or 

hardware at the same level of safety as when it was approved. A properly maintained 

vehicle is less likely to experience an operational problem that would adversely affect 

public safety. Unscheduled maintenance takes care of unforeseen problems. It can also 

be used to correct design or other problems in systems and components. Incorporating 

maintenance into the design phase results in hardware that is easier to maintain. Access 

panels and component access are good examples of this concept. A piece of hardware 

that is easy to maintain is more likely to be maintained correctly. If maintenance is too 

difficult, short cuts and omissions can occur, thereby compromising public safety. A side 

benefit is streamlined maintenance with reduced operational costs. 

6.2. A recommended maintenance program plan should include the following items: 

• Locations and facilities where maintenance will be accomplished. 

• Level of components, such as systems and subsystems, that will be 

maintained. 

• Storage plan for spare parts, materials, and all limited shelf life components, 

to the extent practical. 

Rationale: Identifying the locations and facilities where maintenance will be 

accomplished allows an evaluation to be made of the adequacy of such facilities and 

locations for a given maintenance operation. Conducting maintenance operation without 

affecting public safety is important. Blast and toxic release hazards are the main 

contributors to this concern. Proximity of the public and weather conditions are factors 

in determining the suitability of a location or facility for a maintenance operation. In 

addition, the location and facilities need to meet the appropriate requirements for that 

maintenance operation. For example, if a facility lacks the necessary Ground Support 

Equipment to perform maintenance in a safe manner, public safety could be 

compromised if an accident occurs. Determining the level at which component 

maintenance will be performed is also important. Finally, the use of a storage plan for 

limited shelf life items provides a way to document and inspect the usability of such 

items. At the outset of a program, the storage plan may be rudimentary. This plan should 

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be expanded as operational experience shows what parts and subsystems are consumed 

and what failure rates are experienced. 

6.3. A maintenance plan should include the types of tasks to be performed, 

frequency of maintenance, preventive and corrective maintenance actions, 

personnel numbers and skill levels, tools, and test equipment required to sustain a 

maintenance program to the extent practical. 

Rationale: Providing a list of tasks to be performed will enable a reviewer to identify 

tasks that affect or can potentially affect public safety. The list also serves to ensure tasks 

are performed in a manner that will not affect public safety, and the necessary hazard 

controls are in place. Frequency of maintenance is important to public safety because 

parts and systems that experience wear over time need to be maintained or replaced at 

given intervals. The interval between maintenance cycles is important to ensure no 

failures occur before the part is serviced or replaced. The frequency of maintenance is 

also an important inspection tool to make sure failures do not occur. 

Preventive maintenance ensures public safety by avoiding failures before they occur. 

Corrective maintenance actions ensure public safety by returning a failed part, system, or 

vehicle to the approved state. The operator should have a plan for both preventive and 

corrective maintenance actions. Specifying the numbers and skill levels of people 

involved in the maintenance ensures that qualified people are assigned to a maintenance 

task. Personnel assigned to a maintenance task should be expected to perform 

maintenance tasks according to standard industry practice. For example, have an 

inspector approve safety-critical maintenance and document it. An operator must have 

enough qualified people to ensure the maintenance program plan can be implemented. If 

there are not enough qualified people to support an operation, public safety may be 

compromised by having work done by inexperienced or fatigued personnel. Inexperience 

and fatigue contribute to a higher probability of failure. 

Specifying tools and test equipment is also an important part of a maintenance program 

plan because the right tool is needed to do the job right. For example, improperly torqued 

bolts can pose a public safety threat, such as loose connections to the engine. If special 

tools are used, having the tools properly calibrated and periodically inspected is critical to 

ensuring a safe operation. The calibration program should be consistent with standards 

issued by the National Institute of Standards and Technology. Establishing plans for such 

items as maintenance, schedule, and spare parts may be a long, slow process, and these 

plans should be modified as more data is gathered and more flights are attempted. 

However, vehicle operators should have an understanding of their vehicle systems and 

subsystems that require maintenance, and thus the spare parts required to maintain such 

systems and subsystems (e.g. through bench testing, engineering tests, etc.). 

6.4. The applicant should develop and implement a system that will identify, track, 

and report problems related to maintenance activities of flight hardware and 

software, if any. The applicant should establish a data collection system that can be 

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used to identify failure trends and to communicate “lessons learned” from 

maintenance experience. 

Rationale: Because of the nascent nature of the RLV industry, data collection is 

imperative to determine adequate inspection periods and identify which parts, 

subsystems, or both, require maintenance to ensure public safety. The data can also be 

used to adjust the maintenance program plan based on lessons learned. 

6.5. If subcontractors are used, the applicant should develop appropriate 

maintenance requirements to impose on each subcontractor. The applicant should 

have continuous or periodic review, inspection, and assessment to assure that each 

subcontractor is implementing its maintenance program effectively. 

Rationale: Regardless of who performs the maintenance, the operator is ultimately 

responsible to ensure that the work is accomplished in a way that ensures public safety. 

The operator is liable for any damages resulting from improper maintenance. 

6.6. The applicant should have a Configuration Management System (CMS) to 

ensure that flight configuration correlates to a known, tested configuration of parts, 

systems, subsystems, and software. 

Rationale: Use of a CMS contributes to public safety by helping to ensure that the correct 

parts are used for each configuration and preventing the use of unauthorized parts or 

components. In addition, a CMS ensures traceability of the part or component and 

facilitates tracking items in support of a failure investigation. Configuration management 

is standard industry practice and is supported by ISO 9001 certification. Other 

configuration management recommended practices include participation in a fastener 

integrity program and Government Industry Data Exchange Program. The CMS may be 

rudimentary during the initial development stages of an RLV program, but this system 

should become increasingly formal and extensive as the RLV program matures. 

6.7. The applicant should have an inspection schedule. This schedule should 

include the items to be inspected and specify the periodicity of the inspections. As 

the applicant gains experience, the inspection schedule should be updated to reflect 

actual experience. 

Rationale: Because RLV concepts are widely different, it is not practical for the FAA to 

determine the inspection criteria for RLV equipment. The manufacturer is the best entity 

to determine the required inspection periodicity and associated rationale for each system 

or component. The FAA expects that initial RLV flights will have many systems or 

components that are inspected after every flight. Once sufficient experience exists to 

determine the reliability of various components, subsystems, and systems, the applicant 

should update its inspection schedule. An up-to-date inspection schedule will ensure that 

the applicant has a well-documented inspection plan based on the design and operation of 

the RLV that contributes to public safety and meets the operational needs of the RLV 

developer. 

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7. RLV Support Personnel 

General Notes: 

• One person may perform more than one task/responsibility concurrently. 

• These positions are hypothetical and fulfill the functions of an RLV operations 

and maintenance program. 

7.1. Training Plan 

The RLV operator should create a support personnel training plan and maintain 

records that show training received. 

Rationale: Implementation of a training plan for RLV support personnel is critical for 

making effective RLV operations and maintenance public safety-related decisions. 

7.2. RLV Aerospace Maintenance Technician (RAMT) 

The RAMT should be familiar with and demonstrate practical and hands-on 

knowledge of system and subsystem functions and operational tests that relate to the 

operations and maintenance of particular vehicles. The RAMT should demonstrate 

proficiency in each system or subsystem of the vehicle if that system or subsystem is 

used in the vehicle or support equipment. Each system and subsystem RAMT 

should be identified by name and should have the following skills and qualifications 

for his/her system or subsystem: 

Subject Knowledge 

Understand the function and operation of the applicable system or subsystem. 

Task Knowledge 

Know how to predict, isolate, and resolve problems. 

Know step-by-step procedures of the technician documents. 

Know why and when the task must be done. 

Task Performance 

Perform and complete maintenance tasks. 

The RLV operator may use one or any combination of the following programs and 

models for RAMT approval during its rating assessment process: 

• FAA Airframe, Power Plant Mechanic, or both, certification programs. 

• SpaceTEC Aerospace Technician Certification program. 

• Automotive Service Excellence Certification model. 

Rationale: RLV Aerospace Maintenance Technicians ensure compliance with safetycritical operations and safety-critical maintenance activities in support of safe RLV 

operations. 

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7.3. RLV Aerospace Maintenance Inspector (RAMI) 

The RAMI responsibilities should include quality assurance of RLV scheduled and 

unscheduled maintenance, including interface activities within RLV operator 

operations and processing plans. The RAMI should ensure compliance with all of 

the maintenance requirements developed by the RLV operator. The RAMI should 

have the following skills and qualifications: 

Subject Knowledge 

Understand the requirements, criteria, specifications, and policies regarding the 

vehicle systems and subsystems. 

Task Knowledge 

Know the location of and be able to identify and interpret the vehicle’s systems and 

subsystems procedures. 

Task Performance 

Perform vehicle, facilities, and housekeeping inspections regarding the vehicle’s 

systems and subsystems. 

Rationale: The RAMI ensures compliance with safety-critical operations and 

maintenance activities in support of safe RLV operations. 

7.4. Vehicle Mission Coordinator (VMC) 

The VMC is the mission planner. His or her responsibilities include 

• Defining and filing mission profiles. 

• Collaborating with the responsible air traffic authority (FAA or DoD) having 

jurisdiction over the area of intended use. 

• Coordinating with the launch site operator (LSO). 

• Having the subject knowledge of the FAA air traffic control rules, 

regulations, and operational requirements. 

• Understanding the operational limitations, restrictions, and capabilities of 

the space vehicle and the launch and reentry operations and their associated 

regulatory requirements. 

• Having task knowledge of notification procedures and processes. 

Rationale: Efficient coordination with various requisite air traffic entities will be critical 

to bring about safe, routine aerospace operations. Effective filing of mission profiles, 

including nominal and emergency procedures, is essential to facilitate a safe, smooth 

transition of the National Airspace System (NAS) for commercial space launches. The 

inclusion of the VMC within the collaborative process promotes safe and efficient 

operations of the NAS. 

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8. RLV Operations 

8.1. Flight Safety System-1 

The RLV operator should operate the vehicle such that its explosive potential on the 

ground will be minimized, consistent with safe vehicle operations, during any 

attempted landing, including aborts and contingency landings. 

Rationale: Limiting the explosive potential may enable the RLV to land with less risk to 

the public. The operator should demonstrate how operating procedures minimize 

explosive potential upon landing, including aborts and contingency landings. Explosive 

potential may be caused by such items as liquid propellants, solid propellants, pressure 

vessels, and ordnance. If a vehicle failure prevents a normal landing, the operator should 

operate the vehicle so that, if possible, the vehicle has low explosive potential in the 

event of an impact with the ground. 

If a crash of the RLV would be more hazardous to the public with liquid propellants 

onboard, the operator should vent or disperse onboard liquid propellants during flight. 

Venting propellants may enable the RLV to safely dispose of its fuel and oxidizer in the 

event of an anomaly. A Flight Termination System that ruptures the propellant tanks may 

also be considered as another approach. If the vehicle uses solid rocket motors, they 

could be jettisoned if it is feasible and safe to do so. Pressure vessels should be vented, 

and ordnance should be safed, if practical. A vehicle that does not overfly populated areas 

(such as an oceanic flight path) and has no abort-landing capability would not need this 

capability because an explosive landing would not increase the risk to the public. 

Note that if a vehicle is designed to have a powered landing, then the RLV operator is not 

required to empty the fuel tanks before landing. Safe vehicle operation requires sufficient 

fuel for a powered landing. 

8.2. Flight Safety System-2 

The RLV operator's ability to control the location of the instantaneous impact point 

(IIP) should be extremely reliable unless the IIP cannot reach a densely populated 

area. 

Rationale: Being able to control the IIP allows the operator to decrease the risk to the 

public by preventing the vehicle from crashing in a populated area. An example of this is 

a pilot controlling the flight with a highly reliable, remotely operated, backup thrust 

termination system. Thrust termination provides one means of stopping the movement of 

the IIP. 

8.3. Communications-1 

During launch and reentry, the RLV operator should transmit valid, verified safetycritical data from the RLV to the ground in real-time when practical. The RLV 

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operator should record and store data for later transmittal for periods when realtime communication with the ground is not practical. 

Rationale: The launch vehicle operator’s safety official uses safety critical data to 

monitor the health of the vehicle. Telemetry verifies whether or not the vehicle is 

operating within approved parameters. In the event of a vehicle failure, a detailed 

understanding of the state of the vehicle at the time of the failure may be crucial to 

determine the proper emergency response. 

8.4. Communications-2 

The RLV operator should ensure the continuous recording of safety-critical data 

during licensed operations. The data recording should not depend on the vehicle 

landing safely to retrieve the data. 

Rationale: Licensed operations may include preflight hazardous operations and postflight vehicle safing. Recording data on the ground can assist emergency crews in 

responding if an emergency occurs. In the event of an anomaly that affects public safety, 

recorded data may help the licensee prove that the cause has been correctly determined 

and fixed, thus aiding in obtaining the next flight authorization. Recorded data can be 

replayed to aid in determining what events led to the mishap, thus aiding the mishap 

investigation team. The Columbia Accident Investigation Board clearly credits the high 

level of confidence regarding the cause of the accident to finding the data recorder. 

8.5. Communications-3 

The RLV operator should maintain voice communication among flight crew, 

ground flight control personnel, and air traffic control during licensed operations. 

Rationale: The sharing of mission-related information via voice communication is vital 

to the safe operation of the vehicle, especially during off-nominal conditions. Experience 

has shown that voice communication between crew and ground flight control personnel 

greatly enhances the operator’s ability to respond to emergency situations. Often, 

personnel on the ground are the first to become aware of developing safety-critical 

situations. Voice communication is one of many means of conveying this information to 

the flight crew. Voice communication should be maintained between the flight crew and 

the responsible air traffic authority (FAA or DoD) to ensure safe operations during a 

mission. 

8.6. Communications-4 

The RLV operator should operate the vehicle during licensed operations such that it 

can be tracked. 

Rationale: Tracking data will give flight control personnel real-time data to monitor the 

vehicle predetermined trajectory profile and to alert the crew of the RLV, if manned, of 

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the deviation from the mission profile and for corrective action. Such trajectory deviation 

could induce excessive environmental and loading parameters beyond the design 

parameters of the vehicle. In addition, a vehicle sharing the resources of the NAS will 

have to be tracked by the FAA/ATO. Title 14 C.F.R. 91.215 provides the requirements 

for the reporting of altitude for all civil aircraft operating in the airspace. Unless 

otherwise authorized or directed by FAA/ATO, aircraft operating in the NAS must be 

equipped with an operable coded radar beacon transponder having capabilities outlined in 

14 C.F.R. 91.215. 

8.7. Thermal Protection System-1 

The RLV operator should operate the vehicle within the design-heating flight 

envelope during the entire flight, including ascent and reentry, including a sufficient 

margin of safety. 

Rationale: Heat loads associated with a launch, and in particular a reentry, can be 

substantial. Failure to protect a vehicle from heating loads can cause a catastrophic failure 

of the vehicle and a subsequent impact at an unintended, possibly inhabited, location. The 

operator must determine the flight envelope for the vehicle that ensures no thermal limits 

are exceeded during a flight, including a sufficient margin of safety. The operator should 

keep the vehicle within this flight envelope to withstand the heat loads during nominal 

flight and all safe aborts. The operator should justify the margin of safety based on how 

well the launch environments, reentry environments, and thermal properties of affected 

materials are known. Margin of safety may vary for different portions of the vehicle 

based on risk and level of understanding. For example, if a failure of the thermal 

protection system would result in damage to the vehicle structure that requires substantial 

repairs but does not jeopardize a safe landing, a smaller margin of safety could be used. 

If, on the other hand, a failure of the thermal protection system in another section would 

result in a catastrophic failure of the vehicle, the margin of safety should be higher. 

8.8. Electrical Power System-1 

The RLV operator should operate all safety-critical power sources and electrical 

equipment such that it minimizes the risk of fire, explosion, electrostatic discharge 

or arcing, emission of toxic gasses, and electric shock. 

Rationale: Electrical safety on RLVs includes the prevention of shock, fire, and panic. 

This prevention is to ensure that electrical installations are designed, built, and 

maintained in a manner to promote the safety of the vehicle and any humans who come in 

contact with the vehicle. This prevention is also necessary for safety under normal and 

emergency conditions to protect flight crew, ground crew, and space flight participants 

from electrical hazards. For instance, while working in or around a metal-hulled RLV 

during prelaunch and post-reentry phases a person is usually walking on or touching the 

ground at all times. In addition, the person is usually within reach of power cables or 

electrical equipment in the vehicle containing lethal voltages. Currents that can flow 

from an energized conductor to ground can be very large, even in an ungrounded system; 

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yet even very low currents that pass through the heart can cause death. A fire hazard can 

also exist wherever such electrical potential is present. The threat exists when the 

protective insulation of a wire or cable is damaged by heat, moisture, oils, corrosive 

materials, vibration, abrasion, or impact or where faulty installation or operating 

conditions result in loose connections. 

8.9. Electrical Power System-2 

The RLV operator should operate the vehicle such that the capacity of the power 

sources are sufficient for operations beyond normal mission time to include all 

credible contingency and emergency abort scenarios. 

Rationale: Once committed to flight, the RLV needs enough power to complete the entire 

mission, including a margin for credible contingency and emergency abort scenarios. In 

most cases, the RLV operator pursues a contingency or emergency abort scenario because 

of an anomaly. If the primary power source is not sized to accommodate contingency and 

emergency abort scenarios, then an additional risk may be posed by complications to the 

anomaly introduced by switching from a primary to a backup or secondary power system. 

Power sources considered for an RLV should be sized to handle not only the nominal 

mission but also any emergency contingency scenarios. 

It is not the intended that all RLVs have both a primary source and a secondary power 

source at all times. The need for two power sources would depend on the specific vehicle 

and its operation. However, a secondary power source should function with the same 

capacity as the primary power source rather than merely act as a mission reserve. 

8.10. Structures-1 

The RLV operator should not operate the vehicle beyond its analytically determined 

structural failure point, consistent with ensuring public safety. 

Rationale: The principal function of the structure is to protect the inhabitants and 

components of the vehicle from the external environment. Some structural components 

include, but are not limited to, intertanks, fuselage, wings and control surfaces, engine 

thrust structures, payload bays and doors, and pressurized crew compartments. The 

vehicle structure should be designed to preclude failure by use of adequate design safety 

factors, relief provisions, and safe life characteristics. The vehicle manufacturer should 

establish a set of operational flight parameters and envelopes which will allow the vehicle 

not to exceed its structural failure points. 

8.11. Propulsion-1 

The RLV operator should operate the vehicle such that safety-critical propulsion 

parameters, if any, are monitored and maintained within acceptable limits. 

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Rationale: The safe operation of the propulsion system is normally verified by analyses 

involving the monitored parameters. Unsafe trends can be predicted from monitoring the 

propulsion system performance and lead to a reconfiguration or malfunction procedures 

that result in a safe configuration before reaching a catastrophic condition. 

8.12. Systems Engineering-1 

The RLV operator should consider using functional redundancy for safety-critical 

systems, and where employed, should have processes and procedures for switching 

from primary to secondary systems. 

Rationale: Redundant safety-critical systems provide an additional level of safety for 

operations involving RLVs. Although a redundant system might not always reduce the 

severity of a catastrophic event, such systems allow an operator to reduce the probability 

or frequency of occurrence of that event. If employed, redundancy may ultimately reduce 

the overall risk to the public during the conduct of the operator’s proposed operations. If 

redundancy is not employed, the operator should have justification for not using 

redundant safety-critical systems. For example, a good rationale for not using a redundant 

system would be that the probability of failure is extremely low. 

When implementing redundancy, designers should strive for independency. Independency 

should also extend to physical placement. For instance, the primary and secondary systems 

should not be placed in adjoining locations unless other arrangements are not practical. 

The intent is to maintain the integrity of that system if a problem occurs in the physical 

location of one of the systems. When physically separating the primary and secondary 

systems proves impractical, installation of a bulkhead between the two systems may be 

acceptable. 

8.13. Systems Engineering-2 

The RLV operator should perform systems integration testing to verify that 

individual subsystems perform as expected and do not produce unintentional 

interference with the system as a whole. 

Rationale: In the past, emphasis was placed on equipment design requirements because 

the system was considered the sum of the components (equipment). Today, equipment 

quality has generally improved, and manufacturers have become more aware of product 

safety and liability. Comprehensive industry standards now exist and are used for nearly 

all apparatus. This change allows the review emphasis to shift toward a systems 

engineering approach. Evaluations of equipment should consider overall safety 

comparability. With today's limited resources for plan review and inspection, 

concentration should focus on proper application of equipment, affect of subsystem 

failures on required system functions, and vital safety features. 

For example, the electrical engineering safety guidelines are a combination of equipment 

and system requirements designed to ensure that electrical installations are safe and 

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functional. They consist of general guidelines related to across-the-board good aerospace 

practice and specific requirements related to the equipment, its proper design, installation, 

and use. For safety-critical power sources and electrical equipment, emphasis should be 

on evaluating the system. For example, 

• Is the apparatus enclosure appropriate for the location? 

• Is the fixture adequately grounded to reduce the shock hazard? 

• Is the fixture enclosure fire retardant and not surrounded by combustibles? 

• Will the first upstream over-current device safely clear a fault in the fixture so that 

other parts of the electrical subsystem are not affected? 

• Is the failure indicated and an alternative or back-up provided if it is a vital safety 

system? 

• Do the components go together? 

This example shows how a systems engineering approach can be used for the electrical 

subsystem. It does not imply that individual equipment design details are not important, 

but rather that where there are limiting constraints, an assessment of the performance of 

the overall system should also be given a high priority. 

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