Narrative:

Subject: piper stabilator travel-limiting bolts and nuts. The sketch below indicates the affected parts in the tailcones of most small piper aircraft (PA28, PA32, etc). Some yrs ago while cruising in a PA32 on a family trip I noticed that the electric trim began working in reverse, ie, nose-down trim gave nose-up pitch. Obviously stabilator movement had become restr in the pitch-down direction so the tab was acting as an elevator. We moved all passenger forward, descended and landed safely, as fortunately the pitch-up stabilator travel was unaffected, enabling us to flare for touchdown. Examining the travel-limiting bolts I found that on one of the lower ones the stop nut had loosened, enabling the bolt to unscrew under vibration and so limit the pitch-down travel of the stabilator. I wrote the episode up and sent the description of it to the then-existing piper company, the FAA and the NTSB, with a suggestion that the bolts should be safety-wired instead of merely being fixed in place by stop nuts with a DOT of glue. Thinking about it afterward I realized how lucky we had been that the loose bolt was one of the lower ones, not an upper one which if it had come loose would have dropped down in to the hinge fitting and jammed the stabilator pitch-down. In that case the only hope would have been to roll inverted or do an outside loop in the hope of ejecting the fallen bolt, not recommended maneuvers in the PA32 and probably not ones I would have had the presence of mind to try at the time. Later I read of a fatal piper navajo crash near las vegas that was attributed to these travel-limiting bolt assemblies. Now to the immediate reason for this ASRS report and letter: today I saw for the first time a brand-new PA32 saratoga ii hp. Looking in the tailcone I saw the same accident waiting to happen: bolts with their locking nuts secured only by glue dots! Why not safety-wire those bolts, as is routinely required for every other critical nut or bolt on any airplane? Several yrs have passed since the events recounted above, yet what seemed to me to be an easy and inexpensive safety enhancement has not occurred. Callback conversation with reporter revealed the following information: reporter stated that what prompted his report after so many yrs had past after his experience, and that of an accident he had heard had resulted by this stabilator travel limit design, was the present day new aircraft appeared to have the same design. Since he believes that a positive fix by safety wire is possible at minimum cost, he is surprised to see that nothing apparently was done after his reports to the FAA, NTSB, and the manufacturer. He thinks that the design change may have fallen through the 'cracks'!

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Original NASA ASRS Text

Title: PLT OF A PIPER PA32 (SEL) ALLEGES A FLAW IN THE STABILATOR TRAVEL-LIMITING BOLT AND NUT DESIGN WHICH CAUSED LIMITING ACFT PITCH CTL DURING FLT.

Narrative: SUBJECT: PIPER STABILATOR TRAVEL-LIMITING BOLTS AND NUTS. THE SKETCH BELOW INDICATES THE AFFECTED PARTS IN THE TAILCONES OF MOST SMALL PIPER ACFT (PA28, PA32, ETC). SOME YRS AGO WHILE CRUISING IN A PA32 ON A FAMILY TRIP I NOTICED THAT THE ELECTRIC TRIM BEGAN WORKING IN REVERSE, IE, NOSE-DOWN TRIM GAVE NOSE-UP PITCH. OBVIOUSLY STABILATOR MOVEMENT HAD BECOME RESTR IN THE PITCH-DOWN DIRECTION SO THE TAB WAS ACTING AS AN ELEVATOR. WE MOVED ALL PAX FORWARD, DSNDED AND LANDED SAFELY, AS FORTUNATELY THE PITCH-UP STABILATOR TRAVEL WAS UNAFFECTED, ENABLING US TO FLARE FOR TOUCHDOWN. EXAMINING THE TRAVEL-LIMITING BOLTS I FOUND THAT ON ONE OF THE LOWER ONES THE STOP NUT HAD LOOSENED, ENABLING THE BOLT TO UNSCREW UNDER VIBRATION AND SO LIMIT THE PITCH-DOWN TRAVEL OF THE STABILATOR. I WROTE THE EPISODE UP AND SENT THE DESCRIPTION OF IT TO THE THEN-EXISTING PIPER COMPANY, THE FAA AND THE NTSB, WITH A SUGGESTION THAT THE BOLTS SHOULD BE SAFETY-WIRED INSTEAD OF MERELY BEING FIXED IN PLACE BY STOP NUTS WITH A DOT OF GLUE. THINKING ABOUT IT AFTERWARD I REALIZED HOW LUCKY WE HAD BEEN THAT THE LOOSE BOLT WAS ONE OF THE LOWER ONES, NOT AN UPPER ONE WHICH IF IT HAD COME LOOSE WOULD HAVE DROPPED DOWN IN TO THE HINGE FITTING AND JAMMED THE STABILATOR PITCH-DOWN. IN THAT CASE THE ONLY HOPE WOULD HAVE BEEN TO ROLL INVERTED OR DO AN OUTSIDE LOOP IN THE HOPE OF EJECTING THE FALLEN BOLT, NOT RECOMMENDED MANEUVERS IN THE PA32 AND PROBABLY NOT ONES I WOULD HAVE HAD THE PRESENCE OF MIND TO TRY AT THE TIME. LATER I READ OF A FATAL PIPER NAVAJO CRASH NEAR LAS VEGAS THAT WAS ATTRIBUTED TO THESE TRAVEL-LIMITING BOLT ASSEMBLIES. NOW TO THE IMMEDIATE REASON FOR THIS ASRS RPT AND LETTER: TODAY I SAW FOR THE FIRST TIME A BRAND-NEW PA32 SARATOGA II HP. LOOKING IN THE TAILCONE I SAW THE SAME ACCIDENT WAITING TO HAPPEN: BOLTS WITH THEIR LOCKING NUTS SECURED ONLY BY GLUE DOTS! WHY NOT SAFETY-WIRE THOSE BOLTS, AS IS ROUTINELY REQUIRED FOR EVERY OTHER CRITICAL NUT OR BOLT ON ANY AIRPLANE? SEVERAL YRS HAVE PASSED SINCE THE EVENTS RECOUNTED ABOVE, YET WHAT SEEMED TO ME TO BE AN EASY AND INEXPENSIVE SAFETY ENHANCEMENT HAS NOT OCCURRED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT WHAT PROMPTED HIS RPT AFTER SO MANY YRS HAD PAST AFTER HIS EXPERIENCE, AND THAT OF AN ACCIDENT HE HAD HEARD HAD RESULTED BY THIS STABILATOR TRAVEL LIMIT DESIGN, WAS THE PRESENT DAY NEW ACFT APPEARED TO HAVE THE SAME DESIGN. SINCE HE BELIEVES THAT A POSITIVE FIX BY SAFETY WIRE IS POSSIBLE AT MINIMUM COST, HE IS SURPRISED TO SEE THAT NOTHING APPARENTLY WAS DONE AFTER HIS RPTS TO THE FAA, NTSB, AND THE MANUFACTURER. HE THINKS THAT THE DESIGN CHANGE MAY HAVE FALLEN THROUGH THE 'CRACKS'!

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.