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Vehicle Pressurization (V-IC-26-500): There are four components of this subsystem. The major failure modes are:
- Tubing and Fittings (26-501): Oxidizer leakage may freeze the engine hydraulic control system. This may result in failure of
the S-IC stage and cause launch abort.
- Heat Exchanger LOX (260502b): Leakage of liquid or gaseous oxygen may cause a fire hazard in exhaust ducts, causing possible
damage by burning through. Increased temperature and backpressure may affect turbine operation and stage propulsion.
Hydraulic Control (V-IC-26-600): The Hydraulic Control subsystem has seven components. The major failure modes are:
- Check Valves (26-603b): Failure may prevent flow of ground-supplied hydraulic fuel to the high-pressure fuel duct, which may
cause lack of sufficient fuel pressure to the four-way valve. Start sequence may be delayed by non-functioning throttling valves. Engine damage may be possible due to hard
start and cut-off of the S-IC stage propulsion subsystem.
- Checkout Valve (26-604): Failure of the checkout valve locked in either the “engine” or “ground” position may cause a launch
delay until the problem is corrected. Checkout valve in “engine” position and external or internal leakage may cause a fire hazard and/or propulsion cut-off by the
ignition stage limit timer.
Electrical (V-IC-26-700): The Electrical subsystem has three components. The major failure modes are:
- Start Solenoid (26-701): With failure to operate at the prescribed time, the engine will not start. Expiration of the ignition
stage limit timer will initiate safe cut-off. Actual loss may be launch abort.
- Stop Solenoid (part of engine control valve): Failure to operate will not shut down the engine until pre-valves close, causing
extended cut-off impulse. Extended propulsion system operation and/or damage will cause stage altitude instability and vehicle trajectory deviation.
Flight Instrumentation (V-IC-26-800): The Flight Instrumentation subsystem has two components. The major failure mode is:
- Primary Flight Instrumentation (26-801): Fuel and hot gas leakage at pressure connections will cause a fire hazard at lower
altitude. LOX leakage at pressure connections may cause freezing of hydraulic control lines and preclude engine start.
F-1 Engine Failure Modes from Records
Rocketdyne conducted an analysis of 35
individual F-1 engine failures of code 5 (possible launch abort or mission loss) and classified the failure modes into the following five types [Ref. 6]:
Table 1 — Classification of Failure Modes.
|
Type of Failures
|
Number of Modes
|
Percent of Total
|
|
Fatigue Failures
|
12
|
34
|
|
Seal Failures
|
9
|
26
|
|
Structural Failures
|
8
|
23
|
|
Functional Failures
|
4
|
11
|
|
Hydraulic Phenomenon
|
2
|
6
|
|
Totals
|
35
|
100
|
The distribution of failure modes by design area/component was as follows (R-8099):
Table 2 — Distribution of Failure Modes by Design Areas/Components.
|
Design Area
|
Number of Modes
|
Percent of Total
|
|
Engine Systems
|
10
|
29
|
|
Turbo-Machinery
|
9
|
26
|
|
Thrust Chamber
|
4
|
11
|
|
Gas Generator
|
4
|
11
|
|
Valves
|
4
|
11
|
|
Interconnections
|
2
|
6
|
|
Electrical
|
2
|
6
|
|
Totals
|
35
|
100
|
As per this report [Ref. 6], the most frequent failure mode was fatigue
failure (34% - Table 1). The second most frequent failure was due to seal failure (26% - Table 1), while the third was caused by structural failure (23%
- Table 1). The most vulnerable components in order of frequency were Engine Systems (29%), Turbo-Machinery (26%), Thrust Chamber, Gas Generator, and Valves (11% each).
Significant Engine Failure Modes per Expert Inputs
Face-to-face interviews were conducted from July 1 to July 26, 2002, to
collect data from the memory of the engineers who were associated with the Saturn projects. A total of 24 engineers were contacted, and relevant data
was obtained from 8 engineers who were actively connected with the operation and testing of F-1 engines. These inputs were of a qualitative
nature and indicated the relative risk associated with significant failure modes they experienced. The outcome of the survey indicated that
combustion instability was the worst risk, followed by fuel-mix at injector face and ignition at start. Propellant leakage, combustion chamber nozzle tube
failure and structural failures represented risks of lesser degree.
Conclusion
Though individual data sources vary in identifying failure modes, some common modes appear in all data sources. These failure modes are
combustion instability, fuel-mix at injection face, nozzle tubes, propellant leakage, hydraulic valves, and structural failures. The likelihood of leakage
is high, but severity in most of these cases is not likely to be serious. The mitigation steps consist of enhanced design. Hydraulic valves and structural
failures can be removed by enhancing the design for strength and stress level experienced. Nozzle tube problems may be eliminated by replacing the
tubes by channel design as used in the RD180 model (Russian engine). Combustion instability appears to be a major problem, as it will require
substantial research and experimentation to completely comprehend the principles that control the phenomenon. The effect of combustion instability
is very severe and may cause loss of an engine. The problem with fuel-mix also requires research and time to formulate the principles guiding the
operational efficiency. Rocketdyne report No. R-8099 cited turbo-machinery as a major failure area and likely to be vulnerable to failure as the
components are subjected to extreme temperature difference between compressor and turbine sides mounted on the same shaft separated by bearings.
Acknowledgment
This study was supported by the NASA/ASEE (American Society of
Engineering Education) through the Summer Faculty Fellowship Program in 2002 at the Marshall Space Flight Center in Huntsville, Alabama. Their
support is appreciated. The opinions, interpretations and conclusions are those of the author, and are not necessarily endorsed by either NASA and/or ASEE.
Note: An abridged version of this paper was presented at the International Conference of Industry, Engineering, and Management Systems held in Florida on March 17-18, 2003.
References
- Biggs, Bob. “F-1, the No-Frills Giant.” In Threshold Engineering Journal of Power Technology, No. 8. pp. 20-31. Rockwell
International, Los Angeles Basin Data Services Center, spring 1992.
- “Failure Effect Analysis Saturn V, S- IC Stage, F-1 Engine Subsystem — PFRT Configuration” (RAR 3181-1503). Prepared by M.J.
Rudzinski of Reliability Analysis Unit, Rocketdyne, June 25, 1963.
- NASA Technical Memorandum No. NASA TM – 82424. George C. Marshall Space Flight Center, Alabama. May 1981.
- Bilstein, Roger E. “Stages To Saturn, A Technological History of the Apollo/Saturn Launch Vehicles.” The NASA History Series. Scientific
and Technological Information Branch, 1980. National Aeronautics and Space Administration, Washington DC.
- Saturn V Flight Manual – SA 507, National Aeronautics and Space Administration, August 15, 1969.
- “Study to Accelerate Development by Past of a Rocket Engine” (R-8099). Report of the Contract NAS8-18734. Rocketdyne, A
Division of North American Rockets Corporation.
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