Interpretation ID: 18185a

Mark A. M. Ezra, CEng, MIMechE.
Senne, Kelsey & Associates, Inc.
1154 North Warson Road
St. Louis, MO 63132

Dear Mr. Ezra:

This responds to your request for information regarding installation of a hand operated accelerator control system for mobility impaired persons. I apologize for the delay in responding. You wish to know whether a vehicle that has such a system would meet Federal requirements. Our answer is that it appears our requirements would not be met.

Background: Description of Control System

Your letter explains that you are investigating crashes involving two vehicles modified for quadriplegic drivers. Both crashes involved a system called the Electronic Gas and Brake (EGB) Control, manufactured by EMC, Incorporated. The system for each of the two vehicles was apparently placed on the vehicles by a party other than the original vehicle manufacturer.

Your review determined that both crashes involved failures of the electronic throttle system, resulting from the throttle staying in the open position despite reported efforts by the vehicle operators and their able bodied passengers to return the controls to a position which should have brought the engine to idle and applied the brakes.

Your letter describes the EGB Control system as consisting of a dual battery power supply feeding a control box on which is mounted a single plane joy stick. Movement of the joy stick forwards or rearwards causes a servomotor to rotate to a position proportional to the joystick displacement and open the engine's throttle. You describe the system as follows:

The servomotor is positioned near the vehicle's normal brake pedal and accelerator pedal. It has a drum on the output shaft which has a lever attached to it. When the servomotor turns in the desired direction to cause acceleration of the vehicle, a cable connected to the servomotor drum and the vehicle's accelerator pedal is wound onto the servomotor's drum. This action pulls the accelerator pedal of the vehicle down thus accelerating the vehicle. When the vehicle is to be slowed, the servomotor drives in the opposite direction unwinding the cable from the drum. Attached to the servo drum is an arm. After the drum passes the position corresponding to idle for the accelerator, the arm attached to the servo drum bears on the vehicle's brake pedal arm. As the joy stick is moved rearwards of the neutral position (optionally forward depending on selected settings), this lever pushes proportionally more and more on the brake pedal and so applies the brakes of the vehicle harder and harder. The braking is proportional to the joy stick displacement from its neutral position.

You further write that in the crashes under investigation, you believe that either the electrical power cable to the controller or the electrical servomotor cable from the controller to the servomotor became partially or completely detached. According to your letter, when the power cable becomes disconnected the servomotor will remain in the position it was in last when electrical disconnection took place. If this occurs while the vehicle is being accelerated, the vehicle will continue to accelerate indefinitely and in an uncontrolled manner. If this disconnection occurs while in cruise, then the vehicle can not be slowed since the motor cannot be returned to idle nor the brakes applied.

NHTSA obtained a copy of the EGB-IIF "Installation Guide," issued by EMC, Inc. Page three of the guide describes an EGB-IIF cable called the J1 that is the power connection. The guide describes this cable as "the only cable that will interface the vehicle system directly." Apparently this means that there is only one EGB cable that connects to the source of power on the modified motor vehicle.

Discussion

With this background information, I will address your question, which asks whether a throttle system operating as you describe complies with Standard No. 124.

NHTSA cannot make a determination in an interpretation letter whether a particular vehicle complies with a standard. Matters of compliance with our safety standards can only be determined in the context of an enforcement proceeding. However, we will make general observations about Standard No. 124's requirements, as they would apply to a vehicle with a throttle system such as the one you describe.

Standard No. 124 establishes requirements for the return of a vehicle's throttle to the idle position when the driver removes the actuating force from the accelerator control, or in the event of a severance or disconnection in the accelerator control system.⁽¹⁾ The purpose of the standard is to reduce deaths and injuries resulting from engine overspeed caused by malfunctions in the accelerator control system. The standard requires each new vehicle to meet the requirements specified in S5 of the standard.

S5.1 states:

There shall be at least two sources of energy capable of returning the throttle to the idle position within the time limit specified by S5.3 from any accelerator position or speed whenever the driver removes the opposing actuating force. In the event of failure of one source of energy by a single severance or disconnection, the throttle shall return to the idle position within the time limits specified by S5.3, from any accelerator position or speed whenever the driver removes the opposing actuating force.

Paragraph S5.2 of the standard states:

The throttle shall return to the idle position from any accelerator position or any speed of which the engine is capable whenever any one component of the accelerator control system is disconnected or severed at a single point. The return to idle shall occur within the time limit specified by S5.3, measured either from the time of severance or disconnection or from the first removal of the opposing actuating force by the driver.

The term "driver-operated accelerator control system" is defined in S4 of the standard as "all vehicle components, except the fuel metering device, that regulate engine speed in direct response to movement of the driver-operated control and that return the throttle to the idle position upon release of the actuating force." The EGB control is included within this definition of an accelerator control system. The terms "throttle" and "idle position" are also defined in the standard. We assume that your use of those terms in your letter is consistent with these definitions.

It is unclear from your letter whether the EGB system was installed before or after the first sale of the vehicle to the consumer. A person installing the system on a new, completed, motor vehicle would be considered an "alterer" under 49 CFR Part 567.7, Requirements for persons who alter certified vehicles. Part 567.7 provides that an alterer must place an alterer's label on the vehicle, stating that the vehicle, as altered, conforms to all applicable Federal motor vehicle safety standards affected by the alteration.

It does not appear that a new vehicle, altered by installation of the EGB system, will meet the requirements of Standard No. 124. The installation guide describes the J1 Power cable as "the only cable that will interface the vehicle system directly." It is unclear whether the EGB system meets S5.1, which requires two sources of energy capable of returning the throttle to the idle position and a return to idle in the event of failure of one source of energy. It also appears that if the cable connector is disconnected at the J1 connector of the controller, the throttle will not return to idle as required by S5.2 of the standard.

After the sale of the vehicle to the first purchaser, a motor vehicle manufacturer, dealer, distributor or repair business modifying the vehicle must not "knowingly make inoperative any part of a device or element of design installed on or in a motor vehicle ... in compliance with an applicable motor vehicle safety standard." (See 49 USC 30122, Making safety devices and elements inoperative.) A "motor vehicle repair business" is defined as a "person holding itself out to the public to repair for compensation a motor vehicle or motor vehicle equipment" (49 USC 30122(a)). A person in any of the above-mentioned categories who makes inoperative the vehicle's compliance with S5.1 or S5.2, or any other applicable standard, is subject to civil penalties for violating 30122.

On September 28, 1998 (63 FR 51547), NHTSA issued a notice of proposed rulemaking to exempt some modifications for handicapped persons from the "make inoperative" prohibition. This proposal would generally permit some modifications that have an unavoidable adverse effect on safety equipment or features installed pursuant to certain safety standards. In the proposal, NHTSA tentatively concluded that an exemption would not be made for making inoperative safety features installed pursuant to Standard No. 124, because the agency tentatively believes that compliance with the standard can be maintained without adversely affecting the ability of handicapped persons to operate a vehicle. The agency is reviewing the public comments in response to the notice. We will place of a copy of your letter in the public file for the proposal (docket number NHTSA-98-4332), along with a copy of this response.

I hope this information is helpful. If you have any further questions, please feel free to contact Dorothy Nakama of my staff at this address or by telephone at (202) 366-2992.

Sincerely,
Frank Seales, Jr.
Chief Counsel
ref:124
d.3/26/99

1. Standard No. 124 applies to new, completed motor vehicles, and not to aftermarket components of accelerator control systems. We have not issued a Federal safety standard that directly applies to hand controls. However, hand controls are items of "motor vehicle equipment." Manufacturers of motor vehicle equipment must ensure that their products are free of safety-related defects (49 U.S.C. 30118-30121). In the event that the manufacturer or NHTSA determines that a product contains a safety-related defect, the manufacturer would be responsible for notifying purchasers of the safety-related defect and remedying the defect free of charge. (This "recall" responsibility is borne by the vehicle manufacturer in cases in which the equipment is installed on a new vehicle by or with the express authorization of that vehicle manufacturer.)