[Federal Register Volume 63, Number 148 (Monday, August 3, 1998)]
[Notices]
[Pages 41320-41321]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-20654]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
[Docket No. NHTSA 98-4075]
General Motors; Grant of Application for Decision of
Inconsequential Noncompliance
General Motors Corporation (GM) of Warren, Michigan, determined
that some of its 1997 model Chevrolet Corvettes failed to meet the
requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 124,
``Accelerator Control Systems,'' and filed an appropriate report
pursuant to 49 CFR Part 573, ``Defects and Noncompliance Reports.'' GM
also applied to be exempted from the notification and remedy
requirements of 49 U.S.C. Chapter 301--``Motor Vehicle Safety'' on the
basis that the noncompliance is inconsequential to motor vehicle
safety.
Notice of receipt of the application was published on September 16,
1997, and an opportunity afforded for comment (Docket No. 97-58, Notice
1; 62 FR 48708).
Paragraph S5.2 of FMVSS No. 124 requires the throttle to return to
idle position within the time limits specified in S5.3, whenever any
component of the accelerator control system is disconnected or severed
at a single point. S5.3 requires return to idle within 3 seconds for
any vehicle exposed to temperatures of 0 degrees to -40 degrees F (-18
degrees to -40 degrees C). During the 1997 model year, GM produced
9,500 Chevrolet Corvettes, which will not comply with FMVSS No. 124
because, when tested with one return spring removed at temperatures
below -26 degrees F, their accelerator pedal module assembly does not
move quickly enough to cause the throttle to return to the idle
position within 3 seconds.
GM described the noncompliance and supported its application with
the following arguments:
The Chevrolet Corvette employs an electronic throttle control which
adjusts the throttle position based on input from the accelerator pedal
position. The accelerator pedal is equipped with three springs, any two
of which are capable of returning the pedal to rest position. Once this
occurs, the throttle returns to idle position approximately 0.2 seconds
later. A test run in early May, however, raised a question about the
ability of the pedal assembly to return at low temperatures.
GM believes that the failure of the pedal assembly to meet the
throttle closing time requirements of FMVSS No. 124 at extremely low
temperatures is inconsequential to motor vehicle safety for the
following reasons.
1. Vehicle Controllability--In the unlikely event that all of the
prerequisites necessary for the noncompliance occurred--that is, a
return spring was disconnected or severed on a pedal assembly with
residual oil, and the vehicle soaked at ambient temperatures below -32
degrees C--the vehicle would continue to be controllable both by the
service brakes and as a result of the Brake Torque Management System.
2. Reliability of the Accelerator Springs--The condition which is
the subject of GM's noncompliance decision can only occur if one of the
return springs is severed or disconnected. The springs in the Corvette
pedal assembly, however, have extremely high reliability and are not
likely to fail in the real world.
3. Condition Requires Extreme Temperatures; Pedal Assembly Warms
Quickly--As mentioned above, the root cause of the noncompliance
condition is the residual oil on the pedal assemblies congealing below
-32 degrees C. Testing at temperatures above that level resulted in
full compliance with the FMVSS No. 124 time limits for all pedal
assemblies tested. Therefore, the ambient temperatures required for the
possibility of this noncompliance to exist are severe. Even if a
vehicle with a disconnected return spring soaked under the necessary
harsh conditions for a sufficient time to congeal the residual oil, the
potential for the noncompliance to occur would exist for only a short
time, because the pedal assembly would warm up quickly with activation
of the vehicle heating system.
4. Condition is Self-correcting--Durability testing indicates that
the condition improves with wear. Bench testing was conducted on five
production pedal assemblies with poor
[[Page 41321]]
return times. The pedals on these assemblies were cycled at room
temperature. Since the vast majority of driving is done with a only
limited pedal movement, each cycle consisted of a 10 per cent
application of pedal travel. Every 2,000 cycles the pedal return at -40
degrees F (-40 degrees C) was checked. The results, shown in Figure 5
[of the application], indicate that most pedals will return within the
specified time limit after 10,000 cycles, and all pedals will easily
meet the time limits after 15,000 cycles.
5. Warranty Data--GM has reviewed recent warranty data for the 1997
Corvette, as well as complaint data. We are unaware of any data
suggesting the subject condition is a real world safety issue.
No comments were received on the application.
FMVSS No. 124 requires that the accelerator control system return
to the idle position in the event of a single point disconnection or
severance of the system in no more than three seconds after the pedal
is released when tested at temperatures from -18 degrees C (0 degrees
F) to -40 degrees C (-40 degrees F also). If the severance is of one of
the three pedal return springs inside the passenger compartment, full
return will take longer than three seconds when the temperature of the
passenger compartment is below -32 degrees C (-26 degrees F).
In this instance, there are many mitigating circumstances that
render the noncompliance inconsequential to safety. First, the
noncompliance does not result in the throttle sticking open at extreme
low temperatures. It merely closes more slowly as a result of congealed
lubricant on a new pedal assembly with tightly fitting parts. (GM
determined that the lubricant was not necessary for long term
durability or corrosion protection and discontinued its use to avoid
further non-compliances.) Even with one return spring removed, the
accelerator pedal returns at least 85 percent of full travel within the
specified time. The worst consequence is merely the duration of an
elevated idle speed for about six seconds, and the vehicle is subject
to this condition only for periods when the temperature in the
passenger compartment is below -26 degrees F. Second, the pedal
assemblies loosen up enough in about 2000 miles of normal driving to
correct the noncompliance. While pedal assemblies with all three return
springs satisfy the performance requirements of FMVSS No. 124 under all
temperature conditions regardless of congealed lubrication or tight fit
of parts, even those with one spring removed will satisfy the standard
after about 2,000 miles of use despite the congealed lubrication at -40
degrees F. It is unlikely that many of the first 9,500 1997 Corvettes,
which had lubricated pedal assemblies, have not yet corrected
themselves. Third, it is extremely unlikely that a pedal return spring
would fail during the first 2000 miles of driving. The springs are
designed for an infinite fatigue life, and they are mounted in a
protected area. Also, they are direct acting compression springs not
dependent upon connections.
In consideration of the foregoing, it is hereby found that General
Motors Corporation has met its burden of persuasion that the
noncompliance discussed herein is inconsequential to motor vehicle
safety, and its application is granted.
(49 U.S.C. 30118 and 30120; delegations of authority at 49 CFR 1.50 and
501.8)
Issued on: July 28, 1998.
L. Robert Shelton,
Associate Administrator for Safety Performance Standards.
[FR Doc. 98-20654 Filed 7-31-98; 8:45 am]
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