Interpretation ID: 77-1.10

TYPE: INTERPRETATION-NHTSA

DATE: January 24, 1977

FROM: AUTHOR UNAVAILABLE; John W. Snow; NHTSA

TO: Transcon Lines

TITLE: FMVSS INTERPRETATION

TEXT: Thank you for your December 6, 1976, letter in which you detail the difficulties experienced by Transcon Lines with certain antilock devices installed in satisfaction of Standard No. 121, Air Brake Systems. You explain that Transcon disconnected both defective and potentially defective antilock devices, and you ask for an explanation of your legal responsibilities for the disconnections under the National Traffic and Motor Vehicle Safety Act (15 U.S.C. @ 1391, et seq.).

After the first purchase of the vehicles for purposes other than resale, the only statutory prohibition against disconnection of safety equipment such as the antilock system is found in @ 108(a)(2)(A) which provides:

@ 108(a)(1) * * * * *

(2)(A) No manufacturer, distributor, dealer, or motor vehicle repair business shall knowingly render inoperative, in whole or part, any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable Federal motor vehicle safety standard [except for repair]. . . .

A person that does not fall a within the enumerated categories is not prohibited from disconnection of the antilock system after purchase. Also, I have spoken to Federal Highway Administration officials who assure me that, because a defective system is involved, the Bureau of Motor Carrier Safety would not require that the system be connected.

Two National Highway Traffic Safety Administration (NHTSA) staff engineers visited the manufacturer of the antilock systems installed on the tractors and trailers in question to investigate the problems you describe. In replacing the sensors on the trailers, it was discovered that improperly manufactured exciter rings (all produced on August 9, 1976) appear to be the source of the problem. In addition to agreeing to replace all the sensors on the trailers in question, the antilock manufacturer has identified all of the sensors manufactured on the day in question and has initiated a defect recall campaign with the NHTSA. In the case of tractor malfunction, a shuttle valve that has been used for years on trailers appears to be sticking because of excessive corrosion on the particular vehicles in question. It is our understanding that the rate of air loss caused by the sticking can be compensated for by the air compressor and does not pose a safety hazard.

With regard to your concern that the systems "fail safe," Standard No. 121 specifies that "electrical failure of any part of the antilock system shall not increase the actuation and release times of the service brakes" (S5.5.1). This provision does not require that the system be completely incapable of malfunction, but the manufacturers have made concerted efforts to make the systems "fail safe." Quite apart from the requirements of the standard, each of the antilock manufacturers faces the same prospects for product liability suits on its antilock products as in the case of any other of its products.

We will continue to monitor the defect campaign efforts of the antilock manufacturer to ensure that an unsafe condition does not arise.

Sincerely,

ATTACH.

December 6, 1976

Please Refer To: File A.599.pm

John W. Snow -- National Highway Traffic Safety Administration

Dear Sir:

This is to inform you that Transcon Lines has disconnected the FMVSS-121 brake systems on all vehicles so equipped operating in our fleet.

In the latter half of 1976, Transcon purchased 100 White Freightliner tractors and 800 Trailmobile trailers equipped with Berg Anti-Wheel Lock Air Brake Systems. Shortly after placing these vehicles in service, two distinct problems surfaced concurrently.

1. After the tractors had operated 20,000-25,000 miles, severe air loss was experienced from the anti-lock control valve (Berg "CALM" valve) in a significant number of tractors. The air leakage occurred in highway operation and resulted in insufficient reservoir pressure to make full service brake application.

2. During the first week in November, several of our drivers reported that they experienced non-functioning trailer brakes at operational speeds above about 45 MPM. When, as an emergency measure enroute, the trailer anti-lock systems were disconnected on the affected trailers, normal brake function was restored for the rest of the trip. Extensive road tests by our maintenance department were conducted on the affected trailers at Los Angeles and Dallas on November 4 and 5. These tests confirmed that with the anti-lock systems connected and apparently functioning, the trailer brakes were inoperative above about 45 MPH. Further, when the anti-lock systems were disconnected, the trailer brakes functioned normally throughout the vehicle speed range. On November 5, the Los Angeles Berg representative was notified of the problem and further testing was conducted at Los Angeles on November 6 to demonstrate the malfunction to him. He subsequently reported his observations to Berg's Engineering Department in Iola, Kansas. ock%Prior to specifying the Berg anti-lock system, Transcon was assured that in the event of any system component failure, the system would be de-activated and revert to a normal (pre-121) branking mode, thereby being a "fail-safe" system. The results on the road and in our tests indicate that the system is far from fail safe, and in fact, appears to hold explosive potential for being extremely dangerous to our drivers, the general highway-using public, our customers' property and our equipment.

In view of these findings, and until the real nature, extent and causes of the problem can be determined and corrected to insure confidence in the reliability of the anti-lock system, we have no responsible choice but to disconnect the anti-lock systems on all our vehicles which are so equipped. Action was immediately taken to disconnect the systems starting November 6. This leaves us with brakes which are adequate to control the vehicles and which are not liable to sudden inexplicable failure on the road.

We are concerned with the legal ramifications of the action we have taken, in light of current federal regulations. However, we do not feel that we could, in any good conscience, continue to operate the anti-lock systems with knowledge of the possibility of catastrophic brake failure without warning. While we have every desire to comply with all applicable federal safety standards and regulations, the safety of our operation must be our prime concern. We want to assure you of our continued cooperation and interest in a satisfactory and safe resolution of this critically important problem. We are hopeful that you can provide some insight and guidance in the resolution of this matter.

Very truly yours,

Benjamin C. Throop -- Senior Vice President, Administration, TRANSCON LINES