This tank was marked as filled inDecember 13, 200S and was installed in the aircraft some time after that date by the 

### manufacturer. The LearJet service center didahistorical research and discovered that they had other aircraft with the same problem. 

### (A/c45-282 discovered onMay 23, 2006 and

### Ale 4SJ208l When and were the halon had discharged could not be

### determined and
no evidence of agent was located so a slow leak can only bJ detected by the indicator on thebottle. Examination of th~ gauge 

### discovered thatwith alittle jarring it

### waspossible torqtate 

### thedial inside the indicator. This was apparent farall of the bottles inquestion that the crimps of the dial faces 

### inside the gauges were inadequate. It is therefore impossible to reli~bly determine the level of the fire retardant for the bottle.

The second issue of concern was that when the technician fired the Squib the tube leading from thebottle was not strong enough to withstand the forces involved. The tube showed evidence of blow out and impact marks on the inside of the ~ube. The tube was installed by the manufacture and ismade of aluminum instefd of the normal steel. Learjet Inc repair center also submitted anMor D for this issue. It is apparent that theholes in the tube during discharge were suffeiciant enough toprevent the blowout disk from rupturing.

It is then recommended in the interest of public safety that all of the aircraft that have one ormore Pacific Scientific fire bottles, part number 33100021-1 be inspected for discharge by weighing the bottle until such time as abetter design for,the gauge is inplace. In this current configuration, should the Halon bottle leak down or the squib charge fire unknowingly, the empty bottle would not be detected during anormal walk arbund. It isalso recommended that the discharge tubes be replace~ with
amaterial that would withstand thepressures and heat of

# t fire bottle discharge. This has thepotential of allowing the aircraft tobe dispatched without the needed fire suppress'on available. It isvery important that the flight crews can be assured that should there be aneed to extinguish a fire ih flight that the bottles have enough retardant toprevent. a total]loss of the aircraft.

INTERIM RESPONSE OF 09-28-2006,

This isan initial response to ~AASafety Recommendations 06.121 and 06.122. The Wichita ACO has requested Learjet investigate the areas discussed by the recommendations and review the appropriateness of implementing these 

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# Jc~ /_ / I -;;-contact James Ga!stad at (316) 946-4135 or the Safety Recommendations Program Manager, Shardul Panchal at (425) 227-21]4.

INTERIM RESPONSE OF 10-10-2007:

We received the initial Learjet Inc. position on the subject Safety Recommendations. The Wichita ACO recognizes the merit of Learjet's question about the absence of Halon as apre-requisite factor fordamage to the discharge line on

## Ale 45-310. Data is needed to show that line damage is limited tobottle discharge without Halon. What is the threshold level of charge and Halon required for adischarge to fracture the blowout disk? Do the blow-out disks fracture correctly? Was the correct squib installed in the bottle? Did the squibs expend the correct amount of energy? Is ICA information needed to assure discharge line integrity following discharge of an empty bottle? Full bottles? 

### I
Following the inadvertent discharge on

### AIC 45-3 10, the tank indicator showed full and the dial face staking was noted tobe inadequate. Subsequent information identified that the epoxy bond between the dial face and gauge was also inadequate. Is the dial face design adequate? Staking the dial face after the epoxy was cured was identified as a process error tobe corrected. Given that the epoxy bond was broken due to
amanufacturing process error, why did the staking fail to retain the dial face? Isaprocess ordesign change needed for the dial facb staking? How many and which aircraft are affected by each defiCienCY!"

What is the response from Pacific scientific to Learjet's

# tery to determine the scope and impact on the entire Learjet fleet? What supplier control activity has Learjet initiated with Pacific scientific?

It is our intent toproceed as identified above. At this tiLe, webelieve that corrective action based on the existing available information would be incorrect. Additional information isneeded to interpret the incident defined in the SR. With many other cas activities and limits to our resources. we believe that the approach outlined above will provide a thorough examination of the incident and any associated fire extinguishing bottle certification or type design issues. We will propose any corrective action deemed necessary as soon as it ispractical to do s6 in the course of
our investigation of these Safety Recommendations. Wewill provide another status update prior to October 31, 2007.

INTERIM RESPONSE OF 03-10-2008:

This isa follow-on response to SRs 06.121 and 06.122 concerning Pacific Scientific fire extinguishing bottles on Learjet Mbdel 45 airplanes. The Wichita Aircraft Certification office (ACO}jisworking with Learjet to resolve the issues identified inADO letter L1 15W-08- 123 dated February 23, 2008. The ACO plans onan acceptable resolution from Learjet by June 2008 at which time we will provide a status update.

If further discussion on this subject isneeded, please contact James Galstad of theACO, at (316) 946-4135 or Shardul Panchal of the Safety Management Branch, P~-117, at (425) 227-2134.