82-01-04 R2 GATES LEARJET: Amendment 39-4296 as amended by amendment 39-4751 is further amended by Amendment 39-5242. Applies to the following models and serial number airplanes certificated in any category:
MODELS
SERIAL NUMBERS
25, 25A
25-003 through 25-066 except 25-061
25B, 25C
25-061, 25-067 through 25-205
COMPLIANCE: Required as indicated, unless previously accomplished.
A) On or before the compliance date (Reference Table I), accomplish the requirements of this paragraph at an FAA certificated maintenance repair agency. However, the modification and inspection of the horizontal stabilizer trim actuator as required in the airplane modification kits referenced in Table I may be performed by another FAA certificated repair agency utilizing qualified technicians who must have recent accessory overhaul experience performing the overhaul and test of the Gates Learjet Horizontal Stabilizer Trim Actuator with the necessary shop equipment (Attachment I hereto) as referenced in Learjet Repair Manual Number 1711-9, or the equivalent equipment.
1) Modify Learjet Models 25, 25A and 25B/C airplane flight control systems, stall warning and control wheel in accordance with the following:
Table I
Gates Learjet Airplane
Modification Kit
Learjet
Models
Compliance
Date/Time
AMK 81-9, *AMK 81-8, and
AMK 80-13 Change 3
25 B/C
On or before
October 31, 1982
AMK 81-10 Change 1,
*AMK 81-8, and AMK 80-13
Change 3
25, 25A
On or before
August 31, 1982
*Kit AMK 81-8 does not apply unless Kit AAK 76-4 has been installed.
B) Required Airplane Maintenance Record entry must be accomplished by the facility performing its portion of the AD as prescribed in paragraph A) of this AD.
C) Insert in the appropriate sections of the existing Airplane Flight Manual (AFM) the FAA approved temporary Airplane Flight Manual Change pertaining to procedures required as a result of the modification of the flight control system in accordance with Airplane Modification Kit, all listed in Table II below. Upon completion of the modifications required by paragraph A) of this AD and the insertion of the temporary AFM changes or equivalent permanent AFM revision, the identified, more restrictive paragraphs of AD 80-19-11 set forth in Table II below are no longer applicable.
Table II
Learjet
AMK
Learjet
Model
AFM Change
Date
Paragraphs of AD
Superseded
AMK 81-10
25, 25A
October 14, 1981
A)2, A)5, A)6
AMK 81-9
25B/C
September 4, 1981
A)2, A)5, A)6
D) To ensure proper operation of the Stall Warning Accelerometer Unit, unless previously inspected in the last 100 hours time-in-service before the effective date of this AD, within the next 50 hours time-in-service and at intervals not to exceed 220 hours time-in-service thereafter, perform the inspection of the Stall Warning Accelerometer in accordance with Gates Learjet Service Bulletin SB 23/24/25-301B, as appropriate.
E) Prior to accomplishing the modification required by paragraph A) of this AD, contact the FAA office noted in paragraph G) of this AD if any modification or alteration has been performed on the affected airplane for further instructions relative to the compatibility of the modification of this AD.
F) Airplanes may be flown in accordance with FAR 21.197 to a location where modifications required by this AD can be accomplished.
G) Alternate means of compliance which provide an acceptable level of safety may be used when approved by the Manager, Wichita Aircraft Certification Office, FAA, Central Region, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209.
All persons affected by this proposal who have not already received the applicable service information from the manufacturer may obtain copies upon request to Gates Learjet Corporation, P.O. Box 7707, Wichita, Kansas 67277. This information may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or FAA, Central Region, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid- Continent Airport, Wichita, Kansas.
Amendment 39-4296 became effective on January 8, 1982.
Amendment 39-4751 became effective on November 1, 1983.
This Amendment 39-5242 becomes effective April 7, 1986.
ATTACHMENT I
The stabilizer actuator test stand (P/N ST-00463) is used to functionally test the stabilizer actuator after overhaul. The physical structure of the test must be capable of withstanding a minimum load of 2500 lbs. without any bending or deformation. The stabilizer actuator is vertically mounted on the test stand with one end stationary and the other end movable through a hydraulic actuator. The test stand consists of the following components:
a. Hydraulic Actuator - The hydraulic actuator is capable of applying a regulated load of 0 2500 lbs. on the stabilizer actuator during the entire extend or retract cycles.b. Hydraulic Pressure Regulator - The pressure regulator is used to select hydraulic pressures applied to the stabilizer actuator during the functional test.
c. Hydraulic Pressure Gauge - The hydraulic pressure gauge is used to monitor hydraulic pressure applied to the stabilizer actuator. The gauge must be certified at least monthly.
d. Digital Position Readout - The digital position readout indictor is used to monitor the travel of the stabilizer actuator. Signals to the indicator are picked up from a rigid mounted linear potentiometer and movable wiper attached to the hydraulic actuator. The digital readout is accurate to 1/1000th of an inch.
e. Linear Scale - A linear scale, graduated in 100th of an inch, is permanently mounted on the test stand to verify the digital readout. A tool of known length is used to verify the linear scale and digital readout before the stabilizer actuator functional test is performed. The tool length must be certified at least yearly.f. Lapse Timer - A lapse timer is coupled to the control switches and the stabilizer actuator to monitor travel time during the extend and retract cycles. The lapse timer must measure seconds to be accurate to 1/100th of a second.
g. Trim Controller - The trim controller is used to simulate two-speed input to the stabilizer actuator primary motor. The trim controller part number is EM 2079-6.
h. Pre-Select Timer - The pre-select timer is used to check stabilizer actuator travel vs. time, voltage and amperage inputs in accordance with the functional test.
i. Power Supply - The power supply is variable through 0-30 volts DC and 0-3 amperes DC.
j. DC Voltmeter - The DC voltmeter must be capable of measuring 0-30 volts DC and must be certified at least yearly. The voltmeter is used to monitor the voltage inputs to the stabilizer actuator in accordance with the functional test.
k. DC Ammeter - The DC ammeter must be capable of measuring 0-30 amperes DC and must be certified at least yearly. The ammeter is used to monitor the amperes inputs to the stabilizer actuator in accordance with the functional test.
l. Millivolt Meter - The millivolt meter is used to monitor the stabilizer actuator linear potentiometer for a smooth and steady signal output. The meter is 0-50 volts graduated in 100 mv increments.
m. Switches - Necessary switches installed to operate the stabilizer actuator primary and secondary motors to extend or retract.
n. A digital or Simpson 260 meter, not a part of the test stand, is used to verify the resistance of the stabilizer actuator linear potentiometer. The digital or Simpson 260 meter must be certified at least every 90 working days.