FAA July 2012 Maintenance Alerts

Mooney: M20J; Blocked Fuel Tank Drains; ATA 2810

A mechanic states, "This aircraft has been repeatedly repaired to correct fuel leaks.  Every drain hole has been covered up, allowing water and fuel to be trapped in the outboard bays.  Also, the drain valve receptacle drain holes were covered with sealant, causing water to collect up to one-half inch before it could be removed over the top of the receptacle — instead of the bottom.  This aircraft experienced a rough running engine on takeoff, most likely (caused) by water ingestion.  Upon opening the tanks, a large amount of water was found still in the tanks, even after a complete draining, and (significant) fuel still trapped in the middle bay.  We have often seen this (fuel drainage problem).  I request a re-evaluation of Airworthiness Directive 85-24-03.  Currently this AD is a one-time directive to inspective fuel tanks for compliance with Mooney Service Bulletin M20-230.  The AD should be made recurring — and mandatory to have all fuel tank repairs made in accordance with Mooney SB M20-230, not just an inspection to (verify) original factory compliance." 

Part Total Time:  (unknown)

Continental: IO550N; Cracked Exhaust Manifold; ATA 7810

(This report references Cirrus SR22 aircraft.)

A technician states, "(I believe this exhaust manifold ...) is a common failure point on these aircraft having turbo-normalizing systems (installed under STC SA10588SC and SE10589SC).  During a pre-buy inspection, (I) found the L/H exhaust manifold assembly was blistered and cracked in two places between cylinder numbers two and four.  This happens because the slip joint becomes frozen due to lack of proper maintenance.  Aggravating this condition is the installed heat shield covers this area from all but the most detailed inspections.  The heat shield may also be reflecting heat back at the exhaust, causing the failure point to always occur beneath the shield.  The manufacturer of the turbo-normalizing system has a service instruction (S/11-01) to address this issue.  However, (I) have noted this inspection is not being performed on a routine basis on several aircraft (serviced) at this facility.  This (defect/report) is only one of several aircraft having identical failures, including one which involved the exhaust pipe separating into two pieces.  (That failure resulted in ...) a 0.1250-inch gap, allowing exhaust gasses into the engine compartment.  In my opinion, aircraft with this turbo-normalizing system installed should have an AD (Airworthiness Directive) with a 50-hour inspection requirement."  (Exhaust P/N:  226850002.)

Part Total Time:  901.0 hours

McCauley: D3A32C406-C; Broken Bearing Race; ATA 6111

(This report references a Beechcraft A36 aircraft.)

"The owner noticed a few specs of oil on the nose cowl," writes this mechanic.  "The propeller was removed to replace the Crankshaft O-ring, but during removal (I) discovered the oil seepage was actually coming from a blade.  The seepage was considered minor and the propeller operation appeared normal.  However, the decision was made to have the propeller sent to a propeller shop and checked out.  (The repair shop) recommended an overhaul due to the calendar time on the prop. During disassembly, the propeller shop discovered one blade was frozen.  Further inspection found the bearing race broken, with approximately one inch (of the race) missing.  Both the blade and the hub had a sizable gouge.  Also, 95 of the ball bearings measured the proper size of 15/32 inches, but one bearing measured 16/32 inches. The blade and hub were not repairable.  It appears the oversized bearing caused the damage.  Complete failure of the propeller was imminent."

Part Total Time:  170.47 hours