# AD 69-23-03: Lower Longeron Inspection - Type: Airworthiness directive - Status: Current - Products: Piper PA-18-150 - Effective: November 15, 1969 - Published: November 15, 1969 - Issued: November 4, 1969 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Small airplane - Amendment: 39-871 - Registered aircraft: 2,135 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/2E73A44E1424F36B8625699900508214.0001 - DRS record last changed: November 21, 2025 - Page: https://openairdocs.org/ad/69-23-03 ## The airworthiness directive 69-23-03 PIPER: Amendment 39-871. Applies to Piper PA-18-150 type airplanes, S/N 18-8809 through 18-8851, except S/N 18-8844 and 18-8849, certificated in all categories. To determine if the lower longerons are made from 1025 steel or the approved 4130 steel, accomplish before further flight the following inspection: (a) Remove the rear seat, look downward through the no sag springs and locate the lower fuselage longerons on the left and right sides of the aircraft. (b) From a point adjacent to the aileron cable pulley measure aft 10 inches on the top of the longeron and perform the following: (1) Using longitudinal strokes sand the top surface of the right and left lower longerons with No. 80 emery cloth, for an area approximately 3 inches in length and 1/2 inch wide. NOTE: No chemical reaction will occur unless this area is thoroughly cleaned down to the bare metal. Use only longitudinal strokes to remove the paint, primer, metalizing or corrosion from this area. (2) Wipe specified area with a clean cloth. (3) Apply one drop of concentrated nitric acid on the sanded area. (4) If the longeron is 1025 steel, the acid drop will boil and turn a yellowish orange or brown. (5) Wipe off the acid spot and neutralize the area with baking soda paste. (6) Wipe surface and wash with water. (7) Prime and paint the test area. (8) If the test indicates (as described above) the longeron is 1025 steel, the aircraft is considered unairworthy and must be grounded until the aircraft is altered in accordance with an alteration approved by the Chief, Engineering and Manufacturing Branch, Eastern Region. (9) The aircraft is considered airworthy, relative to the longeron being 4130 if there is no reaction to the aforementioned acid test, and can be returned to service. Piper Service Bulletin No. 302, dated October 23, 1969 covers this subject. This amendment is effective November 15, 1969 and was effective upon receipt for all recipients of the telegram dated October 24, 1969 which contained this amendment. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS 1A2](https://openairdocs.org/tcds/1A2): Piper Aircraft Inc.; names 1 of 18 models: PA-18-150 ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 2,135 (2,135 by airframe model, 0 by engine model) - Makers: Piper 2,065, Piper/Cub Crafters 46, Cub Crafters 16, Cubs Unlimited/Piper 1, Kurt Lepping 1, Piper/Gerbi Charles R 1, Piper/Johnson C D 1, Piper/Meyer Alfred R 1, Piper/Snyder Matthew A 1, Piper/Sorensen 1 Models with the most aircraft: - [Piper PA-18-150](https://openairdocs.org/model/piper-pa-18-150): 2,065 aircraft (airframe model) - [Piper/Cub Crafters PA-18-150](https://openairdocs.org/model/piper-cub-crafters-pa-18-150): 46 aircraft (airframe model) - [Cub Crafters PA18-150](https://openairdocs.org/model/cub-crafters-pa18-150): 16 aircraft (airframe model) - [Cubs Unlimited/Piper PA 18-150](https://openairdocs.org/model/cubs-unlimited-piper-pa-18-150): 1 aircraft (airframe model) - [Piper/Sorensen PA-18-150](https://openairdocs.org/model/piper-sorensen-pa-18-150): 1 aircraft (airframe model) - [Piper/White Theordore F PA-18-150](https://openairdocs.org/model/piper-white-theordore-f-pa-18-150): 1 aircraft (airframe model) - [Piper/Johnson C D PA-18 150](https://openairdocs.org/model/piper-johnson-c-d-pa-18-150): 1 aircraft (airframe model) - [Piper/Meyer Alfred R PA 18-150](https://openairdocs.org/model/piper-meyer-alfred-r-pa-18-150): 1 aircraft (airframe model) - [Kurt Lepping PA-18-150](https://openairdocs.org/model/kurt-lepping-pa-18-150): 1 aircraft (airframe model) - [Piper/Snyder Matthew A PA-18-150](https://openairdocs.org/model/piper-snyder-matthew-a-pa-18-150): 1 aircraft (airframe model) - [Piper/Gerbi Charles R PA 18-150](https://openairdocs.org/model/piper-gerbi-charles-r-pa-18-150): 1 aircraft (airframe model) All 12 models: https://openairdocs.org/ad/69-23-03/models.md Every aircraft: https://openairdocs.org/ad/69-23-03/aircraft.md Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.