| AD Number | 80-06-02 | Status | Active |
| Effective Date | March 24, 1980 | Issue Date | Not specified |
| Docket Number | Unknown | Amendment | 39-3715 |
| Product Type | ["Aircraft"] | Product Subtype | ["Large Airplane"] |
| CFR Part | --- - Part 39 | CFR Section | N/A |
| Citation | This information is not available. | ||
| Manufacturer(s) | Learjet Inc. |
| Model(s) | 35 35A (C-21A) 36 36A |
80-06-02 GATES LEARJET: Amendment 39-3715. Applies to Models 35 (Serial Numbers 35-001 thru 35-066); 36 (Serial Numbers 36-001 thru 36-017); 35A (Serial Numbers 35-067 thru 35-288); and 36A (Serial Numbers 36-018 thru 36-044) airplanes.
COMPLIANCE: Required as indicated, unless previously accomplished.
To preclude takeoff, or continued flight after a starter assist air start, with an unannunciated failure in the electrical system, accomplish the following:
A) Within the next 10 hours time-in-service after the effective date of this AD, insert the following information in the FAA Approved Airplane Flight Manual and operate the airplane in accordance with these insertions:
1) In Section 1, LIMITATIONS, add the following:
ELECTRICAL SYSTEM
The battery charging bus current limiter and starter disengagement checks, as outlined in STARTING ENGINES, STARTER ASSIST AIRSTART, and/or BEFORE TAKEOFF procedures in Sections II and III of this manual, must be accomplished whenever an engine start using a starter has been performed. These checks require that both engines be operating to perform the check.
2) In Section 2, NORMAL OPERATING PROCEDURES, under the heading STARTING ENGINES, add the following:
(a) Starter Disengagement Check - After both engines are started, perform check as follows:
1. Air Conditioner and Auxiliary Heater - OFF.
2. Both Battery Switches - OFF.
3. Ammeters - Check total current indication less than 100 amps.
4. If total current indication is greater than 100 amps, shut down engines.
NOTE: A total ammeter indication greater than 100 amps indicates that a starter has not disengaged. Subsequent starter and/or engine damage may occur.
If total current indication is less than 100 amps, set both Battery Switches ON.
(b) Battery Charging Bus Current Limiter Check (Serials 35-001 thru 35-147 and 36-001 thru 36-035):
1. Pull MAIN DC BUS TIE circuit breaker.
2. One Generator Switch - OFF. Check ammeter reading on opposite generator, approximately doubles, then switch back to GEN.
3. Opposite Generator Switch - OFF. Check ammeter reading on opposite generator, approximately doubles, then switch back to GEN.
4. Reset MAIN DC BUS TIE circuit breaker.
CAUTION: Failure to meet the above check indicates a malfunction. Replace 275A Current Limiter prior to takeoff. Loss of 275A Current Limiters can lead to loss of essential DC power.
Battery Charging Bus Current Limiter Check (Serials 35-148 thru 35-288 and 36-036 thru 36-044):
1. Test Switch - L CUR LIM.
2. Test Button - Press. Green current limiter light will illuminate and remain on while button is held. The light indicates continuity through the left current limiter. Also the L GEN light will come on and the right generator voltage may be reduced by approximately 2 VDC.
3. Test switch - R CUR LIM.
4. Test Button - Press. Green current limiter light will illuminate and remain on while button is held. The light indicates continuity through the right Current Limiter. Also the R GEN light will come on and the left generator voltage may be reduced by approximately 2 VDC.
CAUTION: Failure of light to remain illuminated indicates a malfunction. Replace 275A Current Limiter prior to takeoff. Loss of 275A Current Limiters can lead to loss of essential DC power.
3) In Section 3, EMERGENCY PROCEDURES, under the headings, ENGINE FAILURE DURING CRUISE and OPERATIONS WITH ONE FUEL COMPUTER INOPERATIVE, add the following after all starter assist engine starts:
(a) Starter Disengagement Check
1. Air Conditioner and Auxiliary Heater - OFF.
2. Both Battery Switches - OFF.
3. Ammeter - Check total current indication less than 100 amps.
4. If total current indication is greater than 100 amps:
a. Both Battery Switches - ON.
b. and as soon as practical.
c. Do not attempt further flights until trouble has been corrected.
NOTE: A total ammeter indication greater than 100 amps indicates that a starter has not disengaged and subsequent starter and/or engine damage may occur.
If total current indication is less than 100 amps, set both Battery Switches ON.
(b) Battery Charging Bus Current Limiter Check (Serials 35-001 thru 35-147 and 36-001 thru 36-035):
1. Pull MAIN DC BUS TIE circuit breaker.
2. One Generator Switch - OFF. Check ammeter reading on opposite generator, approximately doubles, then switch back to GEN.
3. Opposite Generator Switch - OFF. Check ammeter readings on opposite generator, approximately doubles, then switch back to GEN.
4. Reset MAIN DC BUS TIE circuit breaker.
CAUTION: Failure to meet the above check indicates a malfunction. Loss of both 275A Current Limiters can lead to loss of essential DC power.
Battery Charging Bus Current Limiter Check (Serials 35-148 thru 35-288 and 36-036 thru 36-044):
1. Test Switch - L CUR LIM.
2. Test Button - Press. Green current limiter light will illuminate and remain on while button is held. The light indicates continuity through the left current limiter. Also the L GEN light will come on and the right generator voltage may be reduced by approximately 2 VDC.
3. Test Switch - R CUR LIM.
4. Test Button - Press. Green current limiter light will illuminate and remain on while button is held. The light indicates continuity through the right current limiter. Also the R GEN light will come on and the left generator voltage may be reduced by approximately 2 VDC.
CAUTION: Failure of light to remain illuminated indicates a malfunction. Loss of both 275A Current Limiters can lead to loss of essential DC power.
B) Use Paragraph A of this AD, or a duplicate thereof, as an amendment to the FAA Approved Airplane Flight Manual until replaced by Change 9 or 10 to Gates Learjet 35/36 or 35A/36A FAA Approved Airplane Flight Manual, as applicable, both FAA approved February 15, 1980.
C) This AD may be accomplished by the holder of a pilot certificate issued under Part 61 of the Federal Aviation Regulations on any airplane owned or operated by that person, who must make an entry in the airplane maintenance records indicating prescribed compliance with this AD.
D) Any equivalent method of compliance with this Airworthiness Directive must be approved by the Chief, Wichita Engineering and Manufacturing District Office, Federal Aviation Administration, Room 238, Terminal Building No. 2299, Mid-Continent Airport, Wichita, Kansas 67209.
This amendment becomes effective March 24, 1980.