Airworthiness Directive · Amendment 39-14214 · Learjet Model 23, 24, 25, 35, and 36 Airplanes
Learjet Model 23, 24, 25, 35, and 36 Airplanes
This AD applies to the airplanes in Table 1 of this AD, certificated in any category.
| Learjet— | Serial numbers— |
|---|---|
| Model 23 airplanes | 23-003 through 23-090 inclusive. |
| Model 24 airplanes | 24-100 through 24-357 inclusive. |
| Model 25 airplanes | 25-002 through 25-373 inclusive. |
| Model 35 airplanes | 35-002 through 35-676 inclusive. |
| Model 36 airplanes | 36-002 through 36-063 inclusive. |
The FAA is superseding an existing airworthiness directive (AD), which applies to certain Learjet Model 23, 24, 25, 35, and 36 airplanes. That AD currently requires repetitive inspections to detect deterioration of both flappers of the tip tank in each wing of the airplane, and various follow-on actions. The existing AD also requires replacing the flappers with new flappers, and repetitively performing certain other follow-on actions. This new AD requires an inspection of the flappers and flapper assemblies of the tip tank in each wing or a review of the airplane maintenance records to determine the part numbers, and replacement of certain flappers or flapper assemblies if necessary, which ends the existing repetitive inspections. This AD results from numerous continual inspections and the approval of a new, improved flapper and flapper assembly. We are issuing this AD to prevent significant reduction in the lateral control of the airplane due to imbalance of the fuel loads in the wings of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Within 50 hours time-in-service after December 27, 1995 (the effective date of AD 95-25-03), or prior to the accumulation of 600 hours time-in-service since installation of the flapper valve, whichever occurs later: Perform an inspection to detect deterioration (such as cracks, cuts, breaks, splits, or warpage) of both flappers of the tip tank in each wing, in accordance with either Learjet Service Bulletin SB 23/24/25-28-2, dated October 6, 1995 (for Model 23, 24, and 25 airplanes); or Learjet Service Bulletin SB 35/36-28-10, dated October 6, 1995 (for Model 35 and 36 airplanes); as applicable. Repeat this inspection thereafter at intervals not to exceed 600 hours time-in-service.
(1) If no deterioration of the flapper valve is detected, prior to further flight, inspect the flapper valve to ensure proper positioning, inspect the condition of the screws that retain the flapper valve to the plate assembly to ensure that the flapper valve is secure, inspect to ensure that the flapper valve completely covers the opening of the tube and is seated against the tube, and inspect the flapper valve to verify that it moves freely; and accomplish the follow-on corrective actions, if any discrepancy is found. These actions shall be accomplished in accordance with the applicable service bulletin.
(2) If any flapper valve is found to be deteriorated, prior to further flight, replace it with a new flapper valve in accordance with the applicable service bulletin.
(g) Except as provided in paragraph (h) of this AD, at the later of the times specified in paragraphs (g)(1) and (g)(2) of this AD: Replace both flappers of the tip tank in each wing with new flappers in accordance with either Learjet Service Bulletin SB 23/24/25-28-2, dated October 6, 1995 (for Model 23, 24, and 25 airplanes); or Learjet Service Bulletin SB 35/36-28-10, dated October 6, 1995 (for Model 35 and 36 airplanes); as applicable.
(1) Within 5 years since date of installation of the flapper valve, or prior to the accumulation of 2,400 total hours time-in-service on the flapper valve, whichever occurs earlier.
(2) Within 50 hours time-in-service after December 27, 1995.
(h) For airplanes on which the age and time-in-service of the flapper valve cannot be determined: Within 50 hours time-in-service after December 27, 1995, replace both flappers of the tip tank in each wing in accordance with either Learjet Service Bulletin SB 23/24/25-28-2, dated October 6, 1995 (for Model 23, 24, and 25 airplanes); or Learjet Service Bulletin SB 35/36-28-10, dated October 6, 1995 (for Model 35 and 36 airplanes); as applicable.
(i) Within 600 hours time-in-service following replacement of any flapper valve in accordance with the requirements of this AD, and thereafter at intervals not to exceed 600 hours time-in-service: Accomplish the requirements of paragraph (f) of this AD.
Within 600 hours time-in-service since last replacement of any flapper valve in accordance with the requirements of this AD, or within 90 days after the effective date of this AD, whichever occurs later, inspect the flappers and flapper assemblies of the tip tank in each wing to determine their part numbers (P/N). The raised letter and numbers “S-461” on the convex side of the flappers can identify these parts. Instead of inspecting the flappers and flapper assemblies, a review of airplane maintenance records is acceptable if the P/N of the flappers and flapper assemblies can be conclusively determined from that review.
(1) If four flappers having P/N 2323006-802 and four flapper assemblies having P/N 2323006-801 are found installed, no further action is required by this paragraph, and the repetitive inspections required by paragraphs (f) and (i) of this AD can be stopped.
(2) If any flapper having P/N 2323006-5 or any flapper assembly having P/N 2323006-6 is found installed, within 600 hours time-in-service since last replacement of any flapper valve in accordance with the requirements of this AD, replace the flapper valve with a new flapper valve or replace the flapper assembly with new or modified and reidentified assembly, as applicable. The replacement must be done in accordance with the Accomplishment Instructions of Bombardier Service Bulletin SB 23/24/25-28-7, Revision 2, dated May 9, 2001 (for Model 23, 24, and 25 airplanes); or Bombardier Service Bulletin SB 35/36-28-14, Revision 2, dated May 9, 2001 (for Model 35 and 36 airplanes); as applicable. Accomplishment of the replacement ends the repetitive inspections required by paragraphs (f) and (i) of this AD.
As of the effective date of this AD, no person may install a flapper having P/N 2323006-5 or a flapper assembly having P/N 2323006-6, on any airplane.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
