Airworthiness Directive · Amendment 39-11746 · REVO, Incorporated Models Lake LA-4, Lake LA-4A, Lake LA-4P, Lake LA-4-200, and Lake Model 250 Airplanes
REVO, Incorporated Models Lake LA-4, Lake LA-4A, Lake LA-4P, Lake LA-4-200, and Lake Model 250 Airplanes
This AD applies to the following model and serial number airplanes, certificated in any category; that incorporate any of the wing spar part numbers (or FAA-approved equivalent part numbers) that are specified below the airplane models and serial numbers:
| Model | Serial Nos. |
|---|---|
| Lake LA 4 | 246 through 421, 423 through 429, 445, and 446. |
| Lake LA-4A | 244 and 245. |
| Lake LA-4P | 121. |
| Lake LA-4 200 | 422, 430 through 444, and all serial numbers after 446. |
| Lake Model 250 | 1 through 232. |
| Wing spar parts | Part Nos. |
|---|---|
| Upper Spar Cap Angles | 2-1610-015 and 2-1610-016. |
| Lower Spar Cap Angles | 2-1610-075 and 2-1610-076. |
| Upper Spar Doublers | 2-1610-061 and 2-1610-081 and 2-1610-065. |
| Lower Spar Doublers | 2-1610-063 and 2-1610-083. |
This amendment adopts a new airworthiness directive (AD) that applies to certain REVO, Incorporated (REVO) Models Lake LA-4, Lake LA- 4A, Lake LA-4P, Lake LA-4-200, and Lake Model 250 airplanes. This AD requires you to: inspect the left and right wing upper and lower spar doublers for cracks; replace any cracked parts; and incorporate a modification kit. This AD is the result of a report of a fatigue crack found at the second most inboard wing attachment bolt hole on one of the affected airplanes. Similar fatigue cracking has since been reported on seven more of the affected airplanes, including incidents where the fatigue cracking occurred on airplanes with less than 500 hours time-in-service (TIS). The actions specified by this AD are intended to detect and correct cracks in the wing spars, which could result in the wing separating from the airplane with consequent loss of control.
To address this problem, you must accomplish the following:
| Action | When | Procedures |
|---|---|---|
| (1) Inspect the left and right wing upper and lower spar doublers for cracks | At whichever of the following that occurs first: (i) Within the next 50 hours time-in-service (TIS) after June 20, 2000 (the effective date of this AD); or (ii) On or before June 20, 2001 (12 months after the effective date of this AD) | In accordance with the Inspection section of Revo, Inc. Service Bulletin B-79 R1—Revised January 5, 2000. |
| (2) Replace any cracked wing spar doubler with a new part that incorporates the same part number (or FAA-approved equivalent part number) | Prior to further flight after the required inspection | In accordance with the applicable maintenance manual. |
| (3) Incorporate Modification Kit B-79 | Prior to further flight after the required inspection | In accordance with the Kit Installation section of Revo, Inc. Service Bulletin B-79 R1—Revised January 5, 2000. |
After the effective date of this AD, you may not install a wing on any of the affected airplanes, unless one of the following exists:
(1) The wing is new from the factory; or
(2) The inspection, applicable replacement, and kit incorporation requirements of this AD have been accomplished at the time of installation.
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.
