AD 85-22-08 R2 ACTIVE

85-22-08 R2 GATES LEARJET CORPORATION: Amendment 39-5166 as amended by Amendment 39-5223 is further amended by Amendment 39-5296. Applies to Model 55 airplanes, serial numbers 55-003 through 55-086, except those incorporating Service Bulletin 55- 27-7A, Airplane Modification Kit 55-84-7B, or Airplane Accessory Kit 55-83-4.

Compliance required as indicated after the effective date of this AD, unless already accomplished.

To prevent use of incorrect landing distances, 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 for Gates Learjet 55," dated 3/17/81 (on 10/4/85, changes through Change 20, dated 5/10/84, were current):

1. Replace the paragraph "SPOILERS/AUTOSPOILERS/ SPOILER0NS" (pages 1-14) with:
"SPOILERS/SPOILERONS

(a) Spoilers

(1) During landings, a time delay in the spoiler circuit will cause increased spoiler extension times. For a normal landing (spoilerons operative with flaps below 25 degrees), full spoiler extension will require approximately 5 seconds. If the spoilerons are inoperative (AUG AlL light illuminated) or the SPOILER0N circuit breaker (co-pilot's AC bus) is pulled, spoiler extension will require approximately 11 seconds. To account for the increase spoiler deployment times, the following corrections must be applied to the Actual Landing Distance obtained from the ACTUAL LANDING DISTANCE chart in Section V:

Normal Landing: Multiply distance by 1.04.
Spoilerons Inoperative: Multiply distanced 1.15.

(2) If the spoilers are inoperative during flight, the maximum operating altitude is limited to 41,000 feet.

(3) Do not extend spoilers with flaps extended while airborne.

(4) Do not extend spoilers, or operate with spoilers deployed, at speeds above VM0/MM0.

(b) Spoilerons

(1) Spoilerons may be inoperative. If spoileron preflight check fails, the SP0ILERON circuit breaker (co-pilot's AC bus) must be pulled. When the SP0ILERON circuit breaker is pulled, the spoilers and spoilerons will be inoperative in flight and landing spoiler deploy times will increase. With spoilerons inoperative, the maximum operating altitude will be limited to 41,000 feet, and the Actual Landing Distance obtained from Section v must be increased by 15 percent (multiply by 1.15)."

2. Replace the first NOTE under the BEFORE TAXI Spoileron System Check (page 2-20) with the following:

"In the event the spoilerons fail the following check, SP0ILERON circuit breaker (co-pilot's AC bus) - Pull. AUG AlL will illuminate. The spoilers and spoilerons will be inoperative in flight. The spoiler deploy time will be increased for landing. In this event, the maximum operating altitude is limited to 41,000 feet and the Actual Landing Distance obtained from Section V must be increased 15 percent (multiply by 1.15)."

3. The following factors must be applied to the Actual Landing Distance obtained from figure 5-57 (page 5-74):

"Normal Landing: Multiply distance by 1.04
Spoilers Inoperative: Multiply distance by 1.15."

B. In order to comply with the requirements of paragraph A., above, a copy of this AD may be used as a temporary amendment to the Airplane Flight Manual (AFM) and carried in the airplane as part of the AFM until replaced by Gates Learjet-published Temporary Flight Manual (TFM) Changes TFM 85-17, TFM 85-18, and TFM 85-19.

C. Temporary Flight Manual (TFM) Changes TFM 85-17, TFM 85-18, and TFM 85-19 may be removed from the AFM upon incorporation of either Gates Learjet Service Bulletin (SB) 55-27-7A (dated December 12, 1985), Airplane Modification Kit (AMK) 55-84-7B (dated December 12, 1985), or Airplane Accessory Kit (AAK) 55-83-4.

D. For airplanes equipped with thrust reversers modified in accordance with Gates Learjet SB 55-27-7 or AMK 55-84-7A, that modification (SB 55-27-7 or AMK 55-84-7A) must be removed within the next 30 days after the effective date of this AD.

E. For airplanes not equipped with thrust reversers, modification in accordance with Gates Learjet SB 55-27-7 or AMK 55-84-7A constitutes terminating action for the requirements of this AD.

F. Alternate means of compliance with provide an acceptable level of safety may be used when approved by the Manager, Wichita Aircraft Certification Office, FAA, Central Region.

All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Gates Learjet Corporation, P.0. Box 7707, Wichita, Kansas 67277. These documents also may be examined at FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or FAA, Central Region, Wichita Aircraft Certification Office, 1801 Airport Road, Mid-Continent Airport, Wichita, Kansas.

Amendment 39-5166 became effective November 22,1985.

Amendment 39-5223 became effective February 6, 1986.

This Amendment 39-5296 becomes effective May 19, 1986.