Airworthiness Directives; Consolidated Aeronautics Lake Model 250 Airplanes Equipped With a Bendix/King KFC 150 Automatic Flight Control System

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-CE-21-AD; Amendment 39-9051; AD 94-22-02]

Airworthiness Directives; Consolidated Aeronautics Lake Model 250

Airplanes Equipped With a Bendix/King KFC 150 Automatic Flight Control

System

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that

applies to Consolidated Aeronautics Lake Model 250 airplanes equipped

with a Bendix/King KFC 150 automatic flight control system. This action

requires pulling the ``A/P'' and ``TRIM'' circuit breakers, and

fabricating and installing a placard that specifies the use of manual

trim only. An incident where the elevator trim spring lever of a Lake

Model 250 airplane failed to return to neutral following KFC 150

automatic flight control system autotrim operation prompted this

action. The resulting mistrim overpowered the autopilot and caused the

airplane to deviate from its flight path. The actions specified by this

AD are intended to prevent automatic flight control system malfunctions

caused by failure of the elevator autotrim to disengage, which could

result in flight path deviations.

DATES: Effective November 4, 1994.

Comments for inclusion in the Rules Docket must be received on or

before December 30, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Central Region, Office of the Assistant Chief

Counsel, Attention: Rules Docket 94-CE-21-AD, Room 1558, 601 E. 12th

Street, Kansas City, Missouri 64106.

Information that relates to this AD may be examined at the Federal

Aviation Administration (FAA), Central Region, Office of the Assistant

Chief Counsel, Attention: Rules Docket 94-CE-21-AD, Room 1558, 601 E.

12th Street, Kansas City, Missouri 64106.

FOR FURTHER INFORMATION CONTACT: Mr. Roger A. Souter, Aerospace

Engineer, Wichita Aircraft Certification Office, 1801 Airport Road,

Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316)

946-4134; facsimile (316) 946-4407.

SUPPLEMENTARY INFORMATION: The FAA has received a report where the

Bendix/King KFC 150 automatic flight control system malfunctioned

because the elevator trim spring lever on a Consolidated Aeronautics

Lake Model 250 airplane failed to return to neutral following KFC 150

automatic flight control system autotrim operation. This resulted in

the airplane deviating from its flight path.

This KFC 150 automatic flight control system incorporates a

mechanical attachment to the basic airplane's trim system; the basic

airplane in turn has a pilot-actuated spring-loaded lever that controls

a hydraulic actuator. During the original type certification efforts of

the KFC 150 automatic flight control system, a modification was

incorporated that prevents the engage solenoid for the elevator

autotrim servo from remaining occasionally engaged because of an

opposing forced created by the spring. The modification provided a

design where the spring would back-drive the servo motor, relieve the

spring tension, and allow the solenoid to disengage; the solenoid

engages once autotrim begins to run, and disengages when autotrim stops

running.

In the referenced incident, the spring lever of the airplane failed

to return to neutral and the pitch trim continued to run while the KFC

150 automatic flight control system was on autopilot with autotrim

operation. The resulting mistrim overpowered the autopilot and caused

the airplane to deviate from the flight path. The pilot recognized the

problem, disengaged the autopilot, and took control of the airplane.

Initial investigation of the incident reveals that the elevator

autotrim servo did not disengage because of the loads imposed by the

basic airplane's spring lever.

While testing and additional investigation continues in developing

a modification to solve this problem, the FAA has determined that, in

the interim, this Bendix/King KFC 150 automatic flight control system

should not be utilized on Consolidated Aeronautics Lake Model 250

airplanes.

After examining the circumstances and reviewing all available

information related to the incidents described above, the FAA has

determined that AD action should be taken in order to prevent automatic

flight control system malfunctions caused by failure of the elevator

autotrim to disengage, which could result in flight path deviations.

Since an unsafe condition has been identified that is likely to

exist or develop in other Consolidated Aeronautics Lake Model 250

airplanes of the same type design that are equipped with a Bendix/King

KFC 150 automatic flight control system, this AD requires pulling the

``A/P'' and ``TRIM'' circuit breakers, and fabricating and installing a

placard that specifies the use of manual trim only.

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for public

prior comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting immediate flight safety and, thus, was not

preceded by notice and opportunity to comment, comments are invited on

this rule. Interested persons are invited to comment on this rule by

submitting such written data, views, or arguments as they may desire.

Communications should identify the Rules Docket number and be submitted

in triplicate to the address specified above. All communications

received on or before the closing date for comments will be considered,

and this rule may be amended in light of the comments received. Factual

information that supports the commenter's ideas and suggestions is

extremely helpful in evaluating the effectiveness of the AD action and

determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the rule. All comments submitted will be

available, both before and after the closing date for comments, in the

Rules Docket for examination by interested persons. A report that

summarizes each FAA-public contact concerned with the substance of this

AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket No. 94-CE-21-AD.'' The postcard will be date stamped and

returned to the commenter.

The regulations adopted herein will not have substantial direct

effects on the States, on the relationship between the national

government and the States, or on the distribution of power and

responsibilities among the various levels of government. Therefore, in

accordance with Executive Order 12612, it is determined that this final

rule does not have sufficient federalism implications to warrant the

preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency

regulation and that must be issued immediately to correct an unsafe

condition in aircraft, and is not a ``significant regulatory action''

under Executive Order 12866. It has been determined further that this

action involves an emergency regulation under DOT Regulatory Policies

and Procedures (44 FR 11034, February 26, 1979). If it is determined

that this emergency regulation otherwise would be significant under DOT

Regulatory Policies and Procedures, a final regulatory evaluation will

be prepared and placed in the Rules Docket (otherwise, an evaluation is

not required). A copy of it, if filed, may be obtained from the Rules

Docket.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends part 39 of

the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding a new airworthiness directive

to read as follows:

94-22-02 Consolidated Aeronautics: Amendment 39-9051; Docket No. 94-

CE-21-AD.

Applicability: Lake Model 250 airplanes (all serial numbers),

certificated in any category, that are equipped with a Bendix/King

KFC 150 automatic flight control system.

Compliance: Required within the next 10 hours time-in-service

after the effective date of this AD, unless already accomplished.

To prevent automatic flight control system malfunctions caused

by failure of the elevator autotrim to disengage, which could result

in flight path deviations, accomplish the following:

(a) Pull the two circuit breakers, one marked ``A/P'' and the

other marked ``TRIM'', and attach a collar or tie-wrap to them to

prevent resetting.

(b) Fabricate a placard with the words: ``Use manual trim

only.'', and install this placard on the instrument panel within the

pilot's clear view.

(c) Special flight permits may be issued in accordance with

Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR

21.197 and 21.199) to operate the airplane to a location where the

requirements of this AD can be accomplished.

(d) An alternative method of compliance or adjustment of the

initial or repetitive compliance times that provides an equivalent

level of safety may be approved by the Manager, Wichita Aircraft

Certification Office (ACO), 1801 Airport Road, Room 100, Mid-

Continent Airport, Wichita, Kansas 67209. The request shall be

forwarded through an appropriate FAA Maintenance Inspector, who may

add comments and then send it to the Manager, Wichita ACO.

Note: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Wichita ACO.

(e) Information related to this AD may be examined at the FAA,

Central Region, Office of the Assistant Chief Counsel, Room 1558,

601 E. 12th Street, Kansas City, Missouri 64106.

(f) This amendment (39-9051) becomes effective on November 4,

1994.

Issued in Kansas City, Missouri, on October 18, 1994.

John R. Colomy,

Acting Manager, Small Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-26240 Filed 10-24-94; 8:45 am]

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